Hexaaryl biimidazole-based ultraviolet positive linear photoresist and preparation and use methods thereof

Abstract

The invention belongs to the technical field of microelectronic processing materials, and particularly relates to an ultraviolet positive linear photoresist based on hexaaryl biimidazole as well as a preparation method and a use method of the ultraviolet positive linear photoresist. The preparation method comprises the following steps: by taking hexaaryl biimidazole as a photosensitive point, firstly polymerizing oligomer dihydric alcohol, diisocyanate and dihydroxyl functionalized hexaaryl biimidazole to prepare a type of linear ultraviolet photoresist, and then adding a free radical quenching agent into a solution to obtain the light-controllable linear polyurethane photoresist. When the photoresist is used for photoetching, under the irradiation of ultraviolet light, a dynamic C-N covalent bond between two imidazole rings in a hexaaryl biimidazole unit in the linear photoresist is cracked in response to illumination to form an oligomer; meanwhile, the free radical quenching agent is combined with a hexaaryl biimidazole monomer formed after exposure depolymerization to inhibit the recovery of the polymer, so that an area exposed by ultraviolet light can be dissolved in a developing solution, and a high-resolution target positive pattern is obtained.

Description

Technical Field

[0001] The present application belongs to the technical field of microelectronic processing materials, and more specifically, relates to a hexaarylbiimidazole-based ultraviolet positive linear photoresist and a preparation and use method thereof. Background Art

[0002] Photolithography is a technology that transfers patterns from a mask to a substrate such as a silicon wafer through light. Photoresist, as a key material in electronic manufacturing fields such as semiconductors, flat panel displays, and printed circuit boards, occupies a vital position in today's high-tech industry.

[0003] Photoresists are divided into positive photoresists and negative photoresists. Positive photoresists are widely used in the processing of semiconductor devices with high graphic requirements due to their advantages of high contrast and high graphic resolution. The traditional positive photoresist is a phenolic resin-DNQ photoresist system. When this type of photoresist is exposed, its diazo group undergoes Wolfman rearrangement to produce easily soluble carboxylic acid, while the coupling between DNQ and phenolic resin in the unexposed area makes it less soluble. This type of photoresist has good heat resistance and dry corrosion resistance, and has good resolution. However, phenolic resin has non-photobleaching absorption under 248nm ultraviolet light, which makes deep ultraviolet lithography impossible. Later, chemically amplified photoresists were studied to enhance the sensitivity of photoresists to light. The photoacid generator in this type of photoresist produces acid molecules during exposure and further promotes many continuous chemical conversion reactions in the photoresist. However, most current photoresist systems have poor solubility, need to be prepared and used immediately, and cannot be stored for a long time.

[0004] Patent CN115963696A discloses a UV positive photoresist based on a hexaaryl biimidazole molecular switch and a method of use. The photoresist uses hexaaryl biimidazole as a cross-linking unit and a photoresponsive unit, and is a three-dimensional network polymerized photoresist. Under light conditions, the CN covalent bond between the two imidazole rings in the hexaaryl biimidazole is cleaved in response to light, and the polymer is depolymerized to form an oligomer. At the same time, a free radical quencher prevents the oligomer generated by depolymerization after exposure from recovering autonomously, thereby forming an oligomer with an irreversible polymer structure, so that the oligomer formed in the exposed area of ​​the photoresist can be dissolved by a developer, while the unexposed area is insoluble in the developer, and a high-resolution target positive pattern is obtained after development.

[0005] However, the photoresist prepared in the patent document is a three-dimensional network cross-linked structure, and the extension of the placement time will cause the cross-linking degree to further increase, thereby forming an insoluble solid. In order to ensure that the polymer is more soluble after illumination, it is generally controlled that its initial cross-linking degree should not be too high. However, after the advance polymerization, the molecular weight of the polymer will change with the change of the placement time. Therefore, the photoresist in the patent document needs to be prepared and used immediately, the preparation process is complicated, and it is not conducive to the long-term storage and commercial application of the photoresist. In addition, in the patent document, the free radical quencher itself 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, and then affect the film-forming property of the photoresist. The above problems need to be solved urgently. Summary of the invention

[0006] In view of the defects of the prior art, the purpose of the present application is to provide a hexaarylbiimidazole-based UV positive linear photoresist and a preparation and use method thereof, aiming to solve the technical problems of the prior art hexaarylbiimidazole-based UV positive linear photoresist, such as the need to prepare and use immediately, short storage time and poor solubility.

[0007] To achieve the above-mentioned purpose, in a first aspect, the present application provides a hexaaryl biimidazole-based ultraviolet positive linear photoresist, comprising a hexaaryl biimidazole linear polymer and a free radical quencher; The hexaaryl biimidazole linear polymer is a linear polymer obtained by polymerization reaction of a dihydroxy-functionalized hexaaryl biimidazole molecular switch and an oligomer diol with diisocyanate in the presence of a solvent and under the catalytic action of a catalyst; the free radical quencher is a small molecule free radical quencher containing a thiol group and a carboxyl group.

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

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

[0010] Preferably, the molar ratio of the oligomer diol to the dihydroxy functionalized hexaaryl biimidazole molecular switch is 1:1~10:1, and more preferably 2:1~5:1. 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 preferably 2:1~15:1; more preferably 2:1~5:1; the molar amount of the diisocyanate is greater than or equal to the sum of the molar amounts of the oligomer diol and the dihydroxy functionalized hexaaryl biimidazole 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 oligomer diol, the dihydroxy functionalized hexaaryl biimidazole molecular switch and the diisocyanate; and the dihydroxy functionalized hexaaryl biimidazole 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 oligomer diol with a dihydroxy-functionalized hexaarylbimidazole molecular switch, a catalyst and a diisocyanate dissolved in an organic solvent, stirring and heating to cause a polymerization reaction, and then adding the free radical quencher to the solution after the polymerization reaction and stirring evenly to obtain a linear polyurethane photoresist solution based on hexaarylbimidazole.

[0012] According to another aspect of the present invention, there is provided a method for using the 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 hexaarylbiimidazole; (2) exposing the linear polyurethane photoresist film obtained in step (1) to ultraviolet light, so that the CN covalent bond between the two imidazole rings in the hexaaryl biimidazole connecting node of the linear polymer is cleaved, and the polymer is depolymerized to form an oligomer; then adding a developer to develop, the free radical quencher in the photoresist can inhibit the re-polymerization of the hexaaryl biimidazole free radicals, so that the exposed area is easily soluble in the developer, while the unexposed area is insoluble in the developer, and a target positive pattern with high resolution is obtained after development.

[0013] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: (1) The present invention uses hexaaryl biimidazole as a photosensitive unit, firstly polymerizes oligomer diol, diisocyanate and dihydroxy-functionalized hexaaryl biimidazole to prepare a type of linear ultraviolet photoresist, and then adds a free radical quencher to the solution to obtain a light-adjustable linear polyurethane photoresist, wherein the hexaaryl biimidazole is used as a photosensitive unit and has excellent photosensitivity to ultraviolet light and deep ultraviolet light sources, and can be used as a photosensitizer for ultraviolet and deep ultraviolet lithography. The structure type in the photoresist is a linear structure, which has greater solubility, and is in a polymerized state, with higher stability and commercial value. The photoresist can be used in electronic manufacturing fields such as semiconductors, flat panel displays, and printed circuit boards.

[0014] (2) In the present invention, the hexaarylbiimidazole is used as both a photosensitive unit and a connecting unit of the polyurethane. The light-induced structural change of the hexaarylbiimidazole molecule can have an important effect on the molecular weight of the polymer. In the ultraviolet light exposure area, the CN covalent bond of the hexaarylbiimidazole is broken to form two triphenylimidazole free radicals, and the free radical quencher inhibits the repolymerization of the polymer, thereby causing a sharp decrease in the molecular weight of the linear polymer. This enables the system to have a very high lithography resolution, which can reach the submicron level.

[0015] (3) In the present invention, the linear polymer in the exposed area is depolymerized and has very good solubility in the developer, while the polymer in the unexposed area maintains a linear structure and cannot be dissolved by the developer, so that 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 area and the unexposed area, which will obtain a photolithographic pattern with good contrast.

[0016] (4) In the present invention, by regulating the breaking of the CN covalent bond of the hexaarylbiimidazole as a control factor for the change of the polymer structure, the occurrence of defects such as line broadening caused by acid diffusion in traditional diazonaphthoquinone and chemically amplified systems can be avoided.

[0017] (5) In the present invention, the free radical quencher is one of the core components, and its type has an important influence on the entire photolithography effect. It is found that different types of free radical quenchers have different quenching effects, thereby leading to 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 the present invention, mercaptopropionic acid and its analogs are selected as free radical quenchers. The free radical quencher is added after the monomer dihydroxy functionalized hexaaryl biimidazole, oligomer diol and diisocyanate undergo polymerization reaction to form a linear polymer. The free radical quencher does not participate in the polymerization reaction of the hexaaryl biimidazole molecules and will not affect the polymerization effect and film quality of the polymer; and the linear polymer of the present invention itself is 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 the present invention is not only simple in preparation method, but also can be stored for a long time, does not need to be prepared and used immediately, and is suitable for commercial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a technical roadmap for preparing the positive linear polyurethane photoresist based on hexaarylbiimidazole in Example 1.

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

[0020] Figure 3 It is the optical pattern after the photoresist is photolithographically developed in Example 2.

[0021] Figure 4 It is the optical pattern after the photoresist is photolithographically developed in Example 3.

[0022] Figure 5 It is the optical pattern after the photoresist is photolithographically developed in Example 4. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments. The process parameters of the following embodiments that do not specify specific conditions are usually based on conventional conditions.

[0025] The endpoints and any values ​​of the ranges disclosed in the present 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0026] The 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 polymerization reaction of a dihydroxy-functionalized hexaarylbiimidazole molecular switch and an oligomer diol with diisocyanate in the presence of a solvent and under the catalytic action of a catalyst; the free radical quencher is a small molecule free radical quencher containing a thiol group and a carboxyl group.

[0027] In some embodiments, the oligomer diol is polyethylene glycol or polyether diol, preferably polyethylene glycol, and the molecular weight of the oligomer diol is 90 to 1000. The free radical quencher is one or more of 3-mercaptopropionic acid, thioglycolic acid, mercaptobutyric acid and tiopronin.

[0028] In some embodiments, the dihydroxy-functionalized hexaaryl biimidazole molecular switch is a molecular switch with two hydroxyl functional groups obtained by modifying and designing hexaaryl biimidazole as a molecular main body, wherein the hexaaryl biimidazole has a structure shown in the following formula (I):

[0029] Formula (I).

[0030] The hexaarylbiimidazole shown in formula (I) is the main body of the molecule, which is composed of two triphenylimidazoles covalently linked by a CN bond. Under ultraviolet light, the molecule breaks to form two triphenylimidazole free radicals, accompanied by a color change. After the light is removed, the two free radicals are bonded by a CN bond 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, and the electron-withdrawing groups are preferably halogen atoms or nitro groups. It is further preferred to have the structures shown in the following formulas (II) to (VII):

[0032] Formula (2) Formula (3) Formula (4)

[0033] Formula (five) Formula (six) Formula (seven) In formula (II) to formula (VII), R is an alkyl alcohol containing one hydroxyl group, and specifically may be an alkyl alcohol having 1 to 10 carbon atoms, more preferably an alkyl alcohol having 1 to 5 carbon atoms, and even more preferably an alkyl alcohol having 1 to 3 carbon atoms.

[0034] The dihydroxy functionalized hexaaryl biimidazole in the embodiment of the present invention is obtained by modifying the parent structure of formula (I), and any one of the structures of formula (II) to formula (VII) can be used. In addition to the listed structures, the benzene ring of the hexaaryl biimidazole can also be modified with an electron withdrawing group or an electron pushing group, thereby changing the optical properties of the hexaaryl biimidazole and making it have different photosensitivity properties.

[0035] In some embodiments, the free radical quencher is one or more of 3-mercaptopropionic acid, thioglycolic acid, mercaptobutyric acid and tiopronin. The structural formula of 3-mercaptopropionic acid is shown in formula (VIII):

[0036] Formula (VIII).

[0037] Thioglycolic acid (chemical formula C2H4O2S), mercaptobutyric acid (chemical formula C4H8O2S) and tiopronin (chemical formula C5H9NO2S) are analogs of 3-mercaptopropionic acid and can also be used as free radical quenchers of the present 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 for dissolving the oligomer diol, the functionalized hexaaryl biimidazole molecular switch and the free radical quencher.

[0039] In some embodiments, the molar ratio of the oligomer diol to the dihydroxy-functionalized hexaaryl biimidazole molecular switch is 1:1 to 10:1, preferably 2:1 to 5:1. 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 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 oligomer diol and the dihydroxy-functionalized hexaaryl biimidazole molecular switch; the molar amount of the catalyst does not exceed 5% of the total molar amount of the monomers involved in the polymerization, wherein the monomers involved in the polymerization include the oligomer diol, the dihydroxy-functionalized hexaaryl biimidazole molecular switch and the diisocyanate. The catalyst is bis(dimethylaminoethyl)ether, pentamethyldiethylenetriamine, dimethylcyclohexylamine or dibutyltin dilaurate, preferably dibutyltin dilaurate, and the dihydroxy-functionalized hexaarylbiimidazole molecular switch accounts for 10-20% of the total molar amount of the monomers involved in the polymerization.

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

[0041] In some embodiments, the polymerization reaction time is 2-10 hours, and the polymerization reaction temperature is 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 hexaarylbiimidazole; (2) exposing the linear polyurethane photoresist film obtained in step (1) to ultraviolet light, so that the CN covalent bond between the two imidazole rings in the hexaaryl biimidazole connecting node of the linear polymer is cleaved, and the polymer is depolymerized to form an oligomer; then adding a developer to develop, the free radical quencher in the photoresist can inhibit the re-polymerization of the hexaaryl biimidazole free radicals, so that the exposed area is easily soluble in the developer, while the unexposed area is insoluble in the developer, and a target positive pattern with high resolution is obtained after development.

[0042] Further preferably, the oligomer diol in step (1) is polyethylene glycol, and the polyethylene glycol is polyethylene glycol obtained after sufficient water removal under vacuum heating conditions.

[0043] In some embodiments, the drying in step (1) is performed at a temperature of 30 to 70° C. and for a time of 2 to 10 hours.

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

[0045] In some embodiments of the present invention, a positive ultraviolet linear photoresist based on hexaaryl biimidazole is provided. In the photolithography process, the dihydroxy functionalized hexaaryl biimidazole is used not only as a connecting unit but also as a photosensitive unit. In the ultraviolet light exposure area, the CN covalent bond in the hexaaryl biimidazole unit is broken to form two triphenylimidazole free radicals, which are further combined with the surrounding mercaptopropionic acid or its analog quencher to inhibit the recovery of the CN covalent bond so that the hexaaryl biimidazole free radical is polymerized again. Therefore, in the ultraviolet light exposure area, the polymer is depolymerized, and its molecular weight is greatly reduced, and it is easily soluble in the developer, while the unexposed area maintains a linear structure and cannot be dissolved by the developer, resulting in a solubility difference between the exposed and unexposed areas, so that the pattern on the mask can be transferred to the photoresist film and a high contrast is maintained. The photoresist formula adopts a linear polyurethane structure, avoids the defects of cross-linked polymers that need to be prepared and used immediately and poor solubility, can be stored for a longer time, and the preparation process is simpler, which is more conducive to the long-term storage of the photoresist and the commercial application of the product. The hexaarylbiimidazole-based ultraviolet positive linear photoresist provided by the present invention can be applied to the semiconductor industry, printed circuit board field, flat panel display field, and the like.

[0046] The present invention is to mix the components of the photoresist under a nitrogen environment, heat and polymerize to obtain a polymer solution, then add a free radical quencher to the solution to obtain a polyurethane photoresist solution with hexaaryl biimidazole as a photosensitive unit, then drop the photoresist onto a cleaned silicon wafer and spin-coat it into a film, and heat to remove the solvent to form a photoresist film. Under ultraviolet exposure, the CN covalent bond in the hexaaryl biimidazole unit is broken to form two triphenylimidazole free radicals, which are further inhibited by the free radical quencher to polymerize again, so that the molecular weight of the polymer is greatly reduced, and it is easy to be dissolved by a developer, and a solubility difference is generated in the exposed and unexposed areas. This mechanism can be used to transfer the pattern on the mask to the surface of the photoresist film. Experiments have found that the linear photoresist has a higher solubility, and the prepared photoresist solution is a solution that has been polymerized, and the photolithography effect has a high degree of stability, which is conducive to the commercialization of the photoresist. The ultraviolet positive linear photoresist based on the hexaaryl biimidazole molecular switch of the present invention has great commercial potential.

[0047] The process parameters without specific conditions in the following examples are usually based on conventional conditions.

[0048] The following are examples of this application: Example 1 The oligomer diol is polyethylene glycol with a molecular weight of 400 (PEG 400), isophorone diisocyanate (IPDI) is used as the source of isocyanate, 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 (MPA) corresponding to formula (VIII). The structure of 2-OH-HABI is shown in formula (IX):

[0049] Type (9) Type (8) Figure 1 This is a preparation technology route for linear polyurethane positive photoresist with 2-OH-HABI as photosensitive unit and MPA as quencher. Weigh 0.1g PEG 400 Place in a 50 ml round-bottom flask, remove water by vacuum at 75°C for 10 minutes, fill with nitrogen atmosphere and cool to room temperature. Weigh 0.079 g 2-OH-HABI and dissolve in 4 ml anhydrous ethyl acetate, then inject into the PEG 400 Put it in a round-bottom flask and stir it vigorously to mix it evenly. Then add 5 mg of dibutyltin dilaurate catalyst to the flask, weigh 0.097g (about 0.092ml) of IPDI and add it directly to the above reaction flask. After stirring vigorously to fully mix the polymerized monomers, heat it at 75℃ for 3 hours to allow linear polymerization reaction to occur between the monomers. Then add 30 μL of mercaptopropionic acid free radical quencher to the solution to obtain UV positive linear photoresist.

[0050] Place the cleaned silicon wafer on a coating machine, drip the photoresist solution onto the silicon wafer, set the first step speed to 1000rpm, time to 20s; the second step speed to 8000rpm, time to 20s. Place the silicon wafer with the photoresist spun on a heating table at 45℃ for 3 hours to remove the solvent, and obtain a linear contact with 2-OH-HABI as the connecting unit and photosensitive unit, MPA as the quencher, and a mask with a channel width of 5 μm. Contact exposure is performed under a 365nm ultraviolet light source for 100s. After the exposure, it is placed in a mixed solution of H2O:IPA with a ratio of 2:1 for 30s, and then the surface solvent is blown dry with nitrogen to obtain a photolithography pattern with a line width of 5μm.

[0051] Figure 2 Content (a) and content (b) are photolithography patterns of photoresist in different channel size areas after development under an optical microscope. From the small channel size area in content (b), it can be observed that the photoresist surface presents a pattern with a channel width of 5μm. The thickness of the photoresist film after development was characterized by a step profiler, and it can be observed that with the increase of exposure dose, the residual thickness gradually decreases, such as Figure 2 As shown in content (c), it shows that MPA free radical quencher has excellent free radical quenching effect.

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

[0053] Weigh 0.1g PTMG 400 Place in a 50 ml round-bottom flask, remove water under vacuum at 75°C for 10 minutes, fill with nitrogen atmosphere and then switch to nitrogen environment, and cool to room temperature. Weigh 0.079 g of 2-OH-HABI and dissolve in 4 ml of anhydrous ethyl acetate, and inject into the PTMG 400 Put the mixture into a round-bottom flask and stir vigorously to mix it evenly. Then add 5 mg of dibutyltin dilaurate catalyst into the flask, weigh 0.097 g (about 0.092 ml) of IPDI and inject it directly into the above reaction flask. After stirring vigorously to fully mix the polymerized monomers, heat at 75°C for 3 hours to allow linear polymerization reaction to occur between the polymerized monomers. Then add 30 μL of mercaptopropionic acid into the solution to obtain a UV positive linear photoresist.

[0054] Place the cleaned silicon wafer on a coating machine, and drip the photoresist solution onto the silicon wafer. Set the first step speed to 1000 rpm and the time to 20 s; the second step speed to 8000 rpm and the time to 20 s. Place the silicon wafer with the photoresist spun on a heating table at 45°C and heat for 3 hours to remove the solvent, thereby obtaining a linear polyurethane positive photoresist with 2-OH-HABI as the connecting unit and the photosensitive unit and MPA as the quencher. Place the silicon wafer spun with the linear polyurethane photoresist on the stage of the photolithography machine so that it contacts the mask. The mask channel width is 5 μm. Contact exposure is performed under a 365nm light source for 100 s. After the exposure, it is placed in a mixed solution of H2O:IPA with a ratio of 2:1 for 30 s for development, and then the surface solvent is blown dry with nitrogen to obtain the following. Figure 3 Content (a) and Content (b) show photolithography patterns with a line width 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 source of isocyanate, 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. Vacuum and remove water at 75°C for 10 minutes, fill 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, and inject it into the round-bottom flask containing 1,2-decanediol. Stir vigorously to mix it evenly. Then add 5 mg of dibutyltin dilaurate catalyst to the flask, and weigh 0.097 g (about 0.092 ml) of IPDI and directly inject it into the above reaction flask system. After fully mixing the polymerized monomers under vigorous stirring, heat at 75°C for 3 hours to allow linear polymerization reaction to occur between the polymerized monomers. Then add 30 μL of mercaptopropionic acid to the solution to obtain a UV positive linear photoresist.

[0056] Place the cleaned silicon wafer on a coating machine, drip the photoresist solution onto the silicon wafer, set the first step speed to 1000 rpm, time to 20 s; the second step speed to 8000 rpm, time to 20 s. Place the silicon wafer with photoresist spun on a heating table at 45°C and heat for 3 hours to remove the solvent. Place the silicon wafer spun with linear polyurethane photoresist on the stage of the photolithography machine so that it contacts the mask. The mask channel width is 5 μm. Contact exposure is performed under a 365nm light source for 100 s. After the exposure, it is placed in a mixed solution of H2O:IPA with a ratio of 2:1 for 30 s for development, and then the surface solvent is blown dry with nitrogen to obtain the following: Figure 4 Content (a) and Content (b) show photolithography patterns with a line width of 5 μm.

[0057] Example 4 The oligomer diol is polyethylene glycol with a molecular weight of 200 (PEG 200 ), isophorone diisocyanate (IPDI) is used as the source of isocyanate, 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 corresponding to formula (VIII): Weigh 0.1 g PEG 200 Place in a 50 ml round-bottom flask, remove water under vacuum at 75°C for 10 minutes, fill with nitrogen atmosphere and then switch to nitrogen environment, and cool to room temperature. Weigh 0.079 g of 2-OH-HABI and dissolve in 4 ml of anhydrous ethyl acetate, and inject into the PEG 200The mixture was placed in a round-bottom flask and stirred vigorously to mix evenly. Then, 10 mg of dibutyltin dilaurate catalyst was added to the flask, and 0.1455 g of IPDI was directly injected into the reaction flask. After the monomers were fully mixed under vigorous stirring, they were heated at 75°C for 3 hours to allow linear polymerization reaction to occur between the monomers. Then, 50 μL of mercaptopropionic acid was added to the solution to obtain a UV positive linear photoresist.

[0058] Place the cleaned silicon wafer on a coating machine, and drip the photoresist solution onto the silicon wafer. Set the first step speed to 1000 rpm and the time to 20 s; the second step speed to 8000 rpm and the time to 20 s. Place the silicon wafer with the photoresist spun on a heating table at 45°C and heat it for 3 hours to remove the solvent, thereby obtaining a linear polyurethane positive photoresist with 2-OH-HABI as the connecting unit and the photosensitive unit and MPA as the quencher. Place the silicon wafer spun with the linear polyurethane photoresist on the stage of the photolithography machine so that it contacts the mask. The mask channel width is 5 μm. Contact exposure is performed under a 365 nm light source for 100 s. After the exposure, it is placed in a mixed solution of H2O:IPA in a ratio of 2:1 for development for 30 s, and then the surface solvent is blown dry with nitrogen to obtain the following. Figure 5 Content (a) and Content (b) show photolithographic patterns with a line width of 5 μm.

[0059] Example 5 The oligomer diol is polyethylene glycol with a molecular weight of 200 (PEG 200 ), isophorone diisocyanate (IPDI) is used as the source of isocyanate, 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 corresponding to formula (VIII): Weigh 0.05 g PEG 200 Place in a 50 ml round-bottom flask, remove water under vacuum at 75°C for 10 minutes, fill with nitrogen atmosphere and then switch to nitrogen environment, and cool to room temperature. Weigh 0.158 g of 2-OH-HABI and dissolve in 4 ml of anhydrous ethyl acetate, and inject into the PEG 200 The mixture was placed in a round-bottom flask and stirred vigorously to mix evenly. Then, 10 mg of dibutyltin dilaurate catalyst was added to the flask, and 0.1455 g of IPDI was directly injected into the reaction flask. After the monomers were fully mixed under vigorous stirring, they were heated at 75°C for 3 hours to allow linear polymerization reaction to occur between the monomers. Then, 50 μL of mercaptopropionic acid was added to the solution to obtain a UV positive linear photoresist.

[0060] Place the cleaned silicon wafer on a coating machine, drip the photoresist solution onto the silicon wafer, set the first step speed to 1000rpm, time to 20s; the second step speed to 8000rpm, time to 20s. Place the silicon wafer with photoresist on a heating table at 45℃ for 3 hours to remove the solvent, and obtain a linear polyurethane positive photoresist with 2-OH-HABI as a connecting unit and a photosensitive unit and MPA as a quencher. Place the silicon wafer with linear polyurethane photoresist on the stage of the photolithography machine so that it contacts the mask. The mask channel width is 5μm. Contact exposure is performed under a 365nm light source for 100s. After the exposure, it is placed in a mixed solution of H2O:IPA with a ratio of 2:1 for 30s, and then the surface solvent is blown dry with nitrogen to obtain a photolithography pattern with a line width of 5 μm.

[0061] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A UV positive linear photoresist based on hexaarylbiimidazole, characterized in that: It includes a hexaarylbiimidazole linear polymer and a free radical quencher; The hexaaryl biimidazole linear polymer is a linear polymer obtained by polymerization reaction of a dihydroxy-functionalized hexaaryl biimidazole molecular switch and an oligomer diol with a diisocyanate in the presence of a solvent and under the catalytic action of a catalyst; The free radical quencher is a small molecule free radical quencher containing a thiol group and a carboxyl group.

2. The photoresist according to claim 1, characterized in that The oligomer diol is polyethylene glycol or polyether diol; the molecular weight of the oligomer diol is 90 to 1000; and / or, The free radical quencher is one or more of 3-mercaptopropionic acid, thioglycolic acid, mercaptobutyric acid and tiopronin.

3. The photoresist according to claim 1, characterized in that The dihydroxy-functionalized hexaaryl biimidazole molecular switch is a molecular switch with two hydroxyl functional groups obtained by modifying and designing hexaaryl biimidazole as a molecular main body, wherein the hexaaryl biimidazole has a structure shown in the following formula (I): Formula (I).

4. The photoresist according to claim 1, characterized in that The solvent is an organic solvent for dissolving the oligomer diol, the dihydroxy-functionalized hexaarylbimidazole molecular switch and the free radical quencher; the solvent is one or more of anhydrous tetrahydrofuran, ethyl acetate, acetone and acetonitrile.

5. The photoresist according to claim 1, characterized in that The molar ratio of the oligomer diol to the dihydroxy-functionalized hexaarylbiimidazole molecular 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 preferably 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 oligomer diol and the dihydroxy-functionalized hexaaryl biimidazole 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 oligomer diol, the dihydroxy-functionalized hexaaryl biimidazole molecular switch and the diisocyanate; and the dihydroxy-functionalized hexaaryl biimidazole 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 bis(dimethylaminoethyl)ether, pentamethyldiethylenetriamine, dimethylcyclohexylamine and dibutyltin dilaurate.

6. The method for preparing a photoresist according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: mixing an oligomer diol with a dihydroxy-functionalized hexaaryl biimidazole molecular switch, a catalyst and a diisocyanate dissolved in an organic solvent, stirring and heating to cause a polymerization reaction, and then adding the free radical quencher to the solution after the polymerization reaction and stirring evenly to obtain a linear polyurethane photoresist solution based on the hexaaryl biimidazole.

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

8. The method for using the photoresist according to any one of claims 1 to 5, characterized in that: The steps include: (1) spin coating the photoresist solution into a film, and then drying it to obtain a linear polyurethane photoresist film based on hexaarylbiimidazole; (2) exposing the linear polyurethane photoresist film obtained in step (1) to ultraviolet light, so that the CN covalent bond between the two imidazole rings in the hexaaryl biimidazole connecting node of the linear polymer is cleaved, and the polymer is depolymerized to form an oligomer; then adding a developer to develop, the free radical quencher in the photoresist can inhibit the re-polymerization of the hexaaryl biimidazole free radicals, so that the exposed area is easily soluble in the developer, while the unexposed area is insoluble in the developer, and a target positive pattern with high resolution is obtained after development.

9. The method of use according to claim 8, characterized in that: The drying temperature of step (1) is 30-70° C., and the drying time is 2-10 hours.

10. The method of use according to claim 8, characterized in that: The developer is one or more of a mixture of methanol, ethanol, tetrahydrofuran, IPA and water.

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