Negative micron-sized photoresist and preparation method thereof

Abstract

The invention provides a negative micron-sized photoresist and a preparation method thereof, and the preparation method comprises the following steps: adding a sulfur-containing acrylate polymer into a double-boiling-point organic solvent, and fully dissolving the sulfur-containing acrylate polymer under a stirring condition to form a sulfur-rich polymer matrix solution; adding a functional component containing a silicon-oxygen skeleton structure into the sulfur-rich polymer matrix solution to obtain a pre-prepared mixed solution; adding nano shading particles subjected to surface treatment into the pre-prepared mixed solution, and sequentially performing stirring and vacuum defoaming to obtain a precursor solution; and adding a photo-initiation component and a cross-linking promotion component into the precursor solution to obtain the negative micron-sized photoresist. Through the cooperation of the steps, under the condition of not depending on additional technological means, the overall regulation and control of light energy transmission and crosslinking behaviors are realized, so that the problems of uneven thick film crosslinking and structural defects which are easily generated in a traditional single organic polymer photoresist system are solved.

Description

Technical Field

[0001] This invention belongs to the field of ink material technology, and in particular relates to a negative micron-sized photoresist and its preparation method. Background Technology

[0002] Negative micron-scale photoresists are a class of photosensitive polymer materials used for fabricating micron-scale structures. Under illumination, the polymer chains in the exposed area undergo a cross-linking reaction under the action of photoinitiating components, forming a dense and insoluble three-dimensional network structure. The unexposed areas are removed during development, thus achieving the construction of micron-scale patterns. Negative micron-scale photoresists are mainly used in microfabrication fields requiring the fabrication of micron-scale structures with high requirements for film thickness, mechanical strength, and structural stability. They can be used in the fabrication of dielectric isolation structures, buffer layers, and sacrificial layers in microelectronics and integrated circuit manufacturing, and can also be applied to the fabrication of micron-scale support structures, vias, and three-dimensional configurations in microelectromechanical systems (MEMS).

[0003] Traditional photoresist systems typically consist of a single organic polymer, with relatively simple molecular structures and optical properties. Under micrometer-scale thick film conditions, incident light propagating along the thickness direction within the material is prone to excessive penetration or multiple scattering, resulting in a significant uneven distribution of light energy within the film. On one hand, regions closer to the incident light tend to receive excessively high exposure energy, leading to overly rapid crosslinking reactions and excessive crosslinking density. On the other hand, regions farther from the incident light may experience insufficient crosslinking due to insufficient light energy, thus forming a significant crosslinking gradient within the same film layer. This crosslinking gradient is further amplified during subsequent development and curing processes. Due to differences in volume shrinkage and mechanical properties across different regions, stress concentration can easily occur, leading to film defects such as warping, cracking, interface debonding, or localized collapse. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a negative micron-sized photoresist and its preparation method, which aims to solve the problem of uneven exposure and defects that are prone to occur in negative micron-sized photoresists.

[0005] To address the above problems, this invention proposes a method for preparing negative micron-sized photoresist, comprising the following steps: S1. Add sulfur-containing acrylate polymers to a double-boiling-point organic solvent and dissolve them completely under stirring to form a sulfur-rich polymer matrix solution. S2. Add functional components with a silicon-oxygen framework structure to the sulfur-rich polymer matrix solution to obtain a pre-mixed solution; S3. Add surface-treated nano-light-shielding particles to the pre-mixed liquid, and then stir and vacuum degas to obtain the precursor liquid. S4. Add photoinitiating components and crosslinking promoting components to the precursor solution to obtain negative micron-sized photoresist.

[0006] In some embodiments, step S1 includes: S1.1 Place the sulfur-containing acrylate polymer in a vacuum oven and dry it at 40-60℃ and -0.08--0.095MPa for 4-12 hours. At the same time, pre-dehydrate the double-boiling-point organic solvent and store it in a sealed brown bottle for later use. S1.2 Add the double-boiling-point organic solvent to the jacketed glass mixing vessel, add deionized water, turn on the mechanical stirrer and adjust the stirring speed to 300-800 rpm, and stabilize the temperature at 25-35℃ through a constant temperature water bath. S1.3. Add the acrylate polymer containing sulfur structural units to the glass mixing vessel in multiple stages. After each addition, maintain stirring for 10 to 20 minutes. Then raise the temperature to 45 to 55°C and continue stirring for 30 to 90 minutes to obtain a sulfur-rich polymer matrix solution.

[0007] In some embodiments, in step S1, the sulfur-containing acrylate polymer includes at least one of poly(phenylthio)ethyl acrylate, poly(2,2′-thiodiethyl acrylate), and poly(thiodiethanol diacrylate), and the double-boiling-point organic solvent includes at least one of propylene glycol methyl ether acetate / cyclohexanone composite solvent, γ-butyrolactone / methyl isobutyl ketone composite solvent, N-methylpyrrolidone / propylene glycol methyl ether composite solvent, and dimethyl sulfoxide / cyclopentanone composite solvent.

[0008] In some embodiments, step S2 includes: S2.1 Add a mixture of anhydrous ethanol and toluene to a three-necked flask, purge with nitrogen for protection and control the system temperature at 0-10℃. Then add the silane precursor to the three-necked flask, and add deionized water and an acidic catalyst at a stirring speed of 300-600 rpm to allow the silane precursor to undergo controlled hydrolysis and condensation reactions to form a siloxane sol. S2.2 Continue stirring the silica-oxygen structure sol under nitrogen protection for 1-4 hours, and slowly raise the temperature to 20-30℃. Add an organosilane modifier containing unsaturated bonds to the silica-oxygen structure sol and continue stirring for 2-6 hours. After the reaction is completed, perform vacuum distillation or rotary evaporation to obtain a silica-oxygen framework structure functional component solution. S2.3. The silicon-oxygen framework structure functional component solution is dehydrated and stabilized, then transferred to a sealed brown container for storage in the dark. A portion of the sulfur-rich polymer matrix solution is taken as the pre-prepared mother liquor. The silicon-oxygen framework structure functional component solution is added to the pre-prepared mother liquor at 25-35°C and dispersed for 10-30 minutes. The pre-prepared mother liquor is then added back to the remaining sulfur-rich polymer matrix solution dropwise. During the back-addition process, the stirring speed is controlled at 400-900 rpm and the system temperature is maintained at 25-35°C. After the back-addition is completed, the temperature is slowly raised to 40-50°C and stirring is continued for 30-60 minutes to obtain the pre-prepared mixture.

[0009] In some embodiments, in step S2, the silane precursor includes at least one of methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, hydrotriethoxysilane, and phenyltriethoxysilane; the organosilane modifier includes at least one of methacryloxypropyltrimethoxysilane, acryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and allyltrimethoxysilane; and the acid catalyst includes at least one of glacial acetic acid, dilute hydrochloric acid, dilute nitric acid, oxalic acid, and p-toluenesulfonic acid.

[0010] In some embodiments, step S3 includes: S3.1 Place the nano-light-shielding particles in a vacuum oven and dry them at 60-90℃ and -0.08--0.095MPa for 2-6 hours. Add the dried nano-light-shielding particles to anhydrous ethanol and disperse them by ultrasonication for 5-15 minutes. S3.2 Add a surface compatibilizer to the nano-light-shielding particles under continuous stirring, and react at 40-70℃ for 1-4 hours. After the reaction is completed, centrifuge the surface-treated nano-light-shielding particles, and wash and redisperse them with a double-boiling-point organic solvent to obtain a nano-light-shielding particle dispersion. S3.3. At 25-35℃, the dispersion of nano-shading particles is added to part of the pre-mixed solution and sheared and dispersed for 10-30 min. Then it is added back to the remaining pre-mixed solution. During the addition process, the stirring speed is controlled at 400-900 rpm and the system temperature is maintained at 25-35℃. After the addition is completed, stirring is continued for 30-60 min to obtain the dispersion mother liquor. S3.4. Vacuum degassing treatment is performed on the dispersion mother liquor. The degassing temperature is controlled at 25-35℃, the vacuum degree is -0.08--0.095MPa, and the degassing time is 10-30min. Then, it is filtered through a solvent-resistant filter membrane of 0.45μm or 0.2μm. The filtration process is carried out in the dark and under closed conditions to obtain a precursor liquid containing surface-treated nano-light-shielding particles.

[0011] In some embodiments, in step S3, the surface compatibilizer includes at least one of methacryloyloxypropyltrimethoxysilane, acryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and allyltrimethoxysilane; the double-boiling-point organic solvent includes at least one of propylene glycol methyl ether acetate / cyclohexanone composite solvent, γ-butyrolactone / methyl isobutyl ketone composite solvent, N-methylpyrrolidone / propylene glycol methyl ether composite solvent, and dimethyl sulfoxide / cyclopentanone composite solvent; and the nano-light-shielding particles include at least one of nano-titanium dioxide particles, nano-zinc oxide particles, and nano-cerium oxide particles.

[0012] In some embodiments, step S4 includes: S4.1 Transfer the precursor solution to a sealed brown mixing bottle and stir at 25-30°C for 10-20 min. Add the photoinitiating component to the precursor solution under light-protected conditions and stir at 300-600 rpm at 25-35°C for 20-40 min. Add the crosslinking promoting component while stirring continuously, and adjust the stirring speed to 400-800 rpm. Continue stirring at 30-45°C for 30-60 min. S4.2. Vacuum degassing is performed at 25–35℃, with the vacuum degree controlled at –0.08––0.095 MPa and the degassing time at 10–30 min. After degassing, the solution is filtered using a solvent-resistant filter membrane of 0.45 μm or 0.2 μm. The filtration process is carried out under light-proof and sealed conditions. After filtration, the filtrate is collected to obtain negative micron-sized photoresist.

[0013] In some embodiments, in step S4, the photoinitiating component is selected from at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, benzophenone, and isopropylthionthrone, and the crosslinking promoting component includes at least one of trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and ethoxylated trimethylolpropane triacrylate.

[0014] This invention proposes a negative micron-scale photoresist, which is prepared by the method described above.

[0015] Compared with existing technologies, the negative micron-sized photoresist and its preparation method in this invention have the following advantages: Step S1 involves introducing sulfur-containing acrylate polymers and combining them with a double-boiling-point organic solvent to construct a sulfur-rich polymer matrix solution, giving the system strong light absorption and uniform film formation capabilities. Step S2 introduces functional components with a silicon-oxygen framework structure into this matrix, forming a pre-mixed solution where the organic polymer and silicon-oxygen structure coexist, providing buffering and stabilizing effects structurally. Step S3 introduces surface-treated nano-light-shielding particles into the pre-mixed solution, followed by stirring and vacuum degassing to ensure uniform dispersion of the nano-light-shielding particles in the system, thereby effectively controlling the propagation of light in the thickness direction. Step S4 adds photoinitiating and crosslinking promoting components to the precursor solution, enabling the system to form a uniform and fully crosslinked structure under exposure conditions. Through the combination of the above steps, this invention achieves overall control of light energy transfer and crosslinking behavior without relying on additional process methods, thus overcoming the problems of uneven thick-film crosslinking and structural defects that are easily generated in traditional single organic polymer photoresist systems. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a method for preparing negative micron-sized photoresist in one embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] Please refer to Figure 1 This invention proposes a method for preparing negative micron-sized photoresist, the steps of which include: S1. Add the sulfur-containing acrylate polymer to a double-boiling-point organic solvent and dissolve it completely under stirring to form a sulfur-rich polymer matrix solution. The sulfur-containing acrylate polymer includes at least one of poly2-(phenylthio)ethyl acrylate, poly(2,2′-thiodiethyl acrylate), and poly(thiodiethanol diacrylate). The double-boiling-point organic solvent includes at least one of propylene glycol methyl ether acetate / cyclohexanone composite solvent, γ-butyrolactone / methyl isobutyl ketone composite solvent, N-methylpyrrolidone / propylene glycol methyl ether composite solvent, and dimethyl sulfoxide / cyclopentanone composite solvent.

[0019] By dissolving sulfur-containing acrylate polymers in a double-boiling-point organic solvent system, a sulfur-rich polymer matrix solution is constructed, introducing highly polarizable sulfur atom structural units at the molecular level into the negative micron-sized photoresist. The phenylthio groups, thioether bonds, and thioester structures in the sulfur-containing acrylate polymers possess high electron cloud density and refractive contribution, significantly enhancing the material's light absorption and optical controllability. Simultaneously, the double-boiling-point organic solvent, through the synergistic effect of its high and low boiling-point components, provides favorable dissolution kinetics during the dissolution stage and controllable solvent evaporation behavior during the subsequent film formation stage, thus laying the foundation for forming a uniformly thick and densely structured micron-sized negative photoresist.

[0020] Step S1 includes: S1.1 Place the sulfur-containing acrylate polymer in a vacuum oven and dry it at 40-60℃ and -0.08--0.095MPa for 4-12 hours. At the same time, pre-dehydrate the double-boiling-point organic solvent and store it in a sealed brown bottle for later use.

[0021] Vacuum drying of sulfur-containing acrylate polymers effectively removes adsorbed moisture and low-molecular-weight volatiles from the polymer's interior and surface, preventing viscosity fluctuations or localized phase separation caused by moisture during subsequent dissolution and mixing. Simultaneously, dehydration of double-boiling-point organic solvents and sealing and light-protected storage significantly reduces the free water content in the system, inhibiting unexpected hydrolysis or oxidation side reactions of sulfur-containing structures in the solvent environment, thereby improving the chemical stability and batch consistency of sulfur-rich polymer matrix solutions.

[0022] S1.2 Add the double-boiling-point organic solvent to the jacketed glass mixing vessel, add deionized water, turn on the mechanical stirrer and adjust the stirring speed to 300-800 rpm, and stabilize the temperature at 25-35℃ using a constant temperature water bath.

[0023] By isothermally stirring a double-boiling-point organic solvent in a jacketed glass dissolving vessel and introducing a small amount of deionized water to adjust the system polarity, a solvent environment conducive to the unfolding of sulfur-rich polymer segments is created in the initial dissolution stage. This step, by controlling the stirring speed and temperature, allows solvent molecules to form stable convection in space, facilitating the subsequent gradual wetting, swelling, and dissolution of the polymer. This avoids the problem of aggregation or uneven dissolution of sulfur-containing acrylate polymers due to insufficient local solvent in the initial stage, thus improving the homogeneity of the solution.

[0024] S1.3. Add the acrylate polymer containing sulfur structural units to the glass mixing vessel in multiple stages. After each addition, maintain stirring for 10 to 20 minutes. Then raise the temperature to 45 to 55°C and continue stirring for 30 to 90 minutes to obtain a sulfur-rich polymer matrix solution.

[0025] By introducing sulfur-containing acrylate polymers into the solvent system in multiple stages and continuously stirring at moderate temperatures, the polymer chains gradually undergo swelling, deentanglement, and diffusion, effectively reducing the risk of sudden increases in local viscosity caused by rapid polymer addition. Subsequently, moderate heating promotes molecular chain mobility, improving the solubility of sulfur-rich polymers in double-boiling-point solvents. This ensures the uniform distribution of thioether bonds, thioester bonds, and other structures in the solution, resulting in a stable and structurally homogeneous sulfur-rich polymer matrix solution. This provides a stable matrix environment for the subsequent introduction of silicon-oxygen framework structures, nano-shading particles, and photoinitiation systems.

[0026] S2. Add functional components with a silicon-oxygen framework structure to the sulfur-rich polymer matrix solution to obtain a pre-mixed solution.

[0027] By introducing functional components with a silicon-oxygen framework into a sulfur-rich polymer matrix solution, a composite system in which organic sulfur-rich segments and inorganic silicon-oxygen networks coexist synergistically is constructed at the molecular and nanostructure levels. The silicon-oxygen framework structure possesses high bond energy and flexible bond angles, enabling it to form dispersed buffer structural units within the sulfur-rich acrylate matrix. This maintains the optical properties of the system while enhancing the material's structural stability and stress release capability, thereby effectively reducing the risk of warping and cracking of micron-scale thick-film negative photoresists during subsequent processing due to bulk shrinkage or localized stress concentration.

[0028] Step S2 includes: S2.1. Add a mixed solvent of anhydrous ethanol and toluene to a three-necked flask, purge with nitrogen for protection, and control the system temperature at 0–10°C. Then, add the silane precursor to the three-necked flask, and add deionized water and an acidic catalyst while stirring at 300–600 rpm. This allows the silane precursor to undergo controlled hydrolysis and condensation reactions, forming a siloxane sol. The silane precursor includes at least one of methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, hydrotriethoxysilane, and phenyltriethoxysilane. The acidic catalyst includes at least one of glacial acetic acid, dilute hydrochloric acid, dilute nitric acid, oxalic acid, and p-toluenesulfonic acid.

[0029] By subjecting silane precursors to controlled hydrolysis and condensation reactions under low temperature and inert atmosphere conditions, silane molecules modified with organic substituents such as methyl, ethyl, and phenyl gradually form a sol structure with silicon-oxygen bonds as the main chain. The synergistic effect of the low temperature environment and acidic catalyst effectively slows down the hydrolysis and condensation rates, preventing the rapid aggregation of the silicon-oxygen network into a large-scale gel in the early stages. This results in a silicon-oxygen sol with controllable particle size distribution and uniform reactivity, providing a stable reaction platform for subsequent functionalization modification.

[0030] S2.2 Continue stirring the silica-oxygen structure sol under nitrogen protection for 1-4 hours, and slowly raise the temperature to 20-30°C. Add an organosilane modifier containing unsaturated bonds to the silica-oxygen structure sol and continue stirring for 2-6 hours. After the reaction is completed, perform vacuum distillation or rotary evaporation to obtain a silica-oxygen framework structure functional component solution. The organosilane modifier includes at least one of methacryloyloxypropyltrimethoxysilane, acryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and allyltrimethoxysilane.

[0031] By introducing organosilane modifiers containing unsaturated bonds into the silica-oxygen structured sol under elevated temperatures, unsaturated organic structural units are introduced into the silica-oxygen framework through condensation or grafting. This approach maintains the flexibility and stability of the silica-oxygen network while endowing it with the ability to synergistically crosslink or interact with the sulfur-rich acrylate matrix. Further treatment with vacuum distillation or rotary evaporation removes low-boiling-point solvents and byproducts, resulting in a silica-oxygen framework structured functional component solution with high chemical stability and controllable reactivity, which is beneficial for subsequent uniform compounding with the organic matrix.

[0032] S2.3. The silicon-oxygen framework structure functional component solution is dehydrated and stabilized, then transferred to a sealed brown container for storage in the dark. A portion of the sulfur-rich polymer matrix solution is taken as the pre-prepared mother liquor. The silicon-oxygen framework structure functional component solution is added to the pre-prepared mother liquor at 25-35°C and dispersed for 10-30 minutes. The pre-prepared mother liquor is then added back to the remaining sulfur-rich polymer matrix solution dropwise. During the back-addition process, the stirring speed is controlled at 400-900 rpm and the system temperature is maintained at 25-35°C. After the back-addition is completed, the temperature is slowly raised to 40-50°C and stirring is continued for 30-60 minutes to obtain the pre-prepared mixture.

[0033] By dehydrating and stabilizing the solution of the silicon-oxygen framework functional components, and using a stepwise introduction and re-addition of the pre-prepared mother liquor, the silicon-oxygen framework structure is progressively dispersed and structurally adapted in the sulfur-rich polymer matrix. This method effectively avoids localized excessive concentrations or phase separation caused by the one-time addition of silicon-oxygen functional components. Simultaneously, under moderate temperature conditions, it promotes stable physical entanglement and interfacial interactions between the silicon-oxygen framework and the sulfur-rich polymer segments, thereby obtaining a structurally uniform and well-compatible pre-mixed solution. This provides a stable matrix for the subsequent introduction of nano-light-shielding particles and photoinitiation systems.

[0034] S3. Add surface-treated nano-light-shielding particles to the pre-mixed liquid, and then stir and vacuum degas to obtain the precursor liquid.

[0035] By introducing surface-treated nano-light-shielding particles into the pre-mixed solution, an inorganic functional phase with light-modulating capabilities is constructed in the system, significantly enhancing the absorption and shielding ability of negative micron-scale photoresist while maintaining film uniformity. The introduction of nano-light-shielding particles effectively suppresses light scattering and excessive penetration within micron-scale thick films, improves the uniformity of exposure energy distribution along the thickness direction, thereby enhancing the imaging stability and structural fidelity of negative photoresist under micron-scale processing conditions.

[0036] Step S3 includes: S3.1 Place the nano-light-shielding particles in a vacuum oven and dry them at 60-90℃ and -0.08--0.095MPa for 2-6 hours. Add the dried nano-light-shielding particles to anhydrous ethanol and disperse them by ultrasonication for 5-15 minutes.

[0037] Vacuum drying of the nano-light-shielding particles effectively removes adsorbed water and residual volatiles from the particle surface, reducing the risk of particle agglomeration and interfacial instability caused by moisture during subsequent dispersion. The dried nano-light-shielding particles are then introduced into anhydrous ethanol and ultrasonically dispersed, transforming the particles from a primary agglomerated state to a dispersed state in the solvent. This significantly increases the specific surface area exposure of the nano-light-shielding particles, creating favorable conditions for uniform coating with surface compatibilizers and interfacial modification.

[0038] S3.2. Under continuous stirring, a surface compatibilizer is added to the nano-light-shielding particles, and the reaction is carried out at 40-70°C for 1-4 hours. After the reaction is completed, the surface-treated nano-light-shielding particles are centrifuged and washed and redispersed using a double-boiling-point organic solvent to obtain a nano-light-shielding particle dispersion. The surface compatibilizer includes at least one of methacryloyloxypropyltrimethoxysilane, acryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and allyltrimethoxysilane. The double-boiling-point organic solvent includes at least one of propylene glycol methyl ether acetate / cyclohexanone composite solvent, γ-butyrolactone / methyl isobutyl ketone composite solvent, N-methylpyrrolidone / propylene glycol methyl ether composite solvent, and dimethyl sulfoxide / cyclopentanone composite solvent.

[0039] By adding an organosilane-based surface compatibilizer containing unsaturated bonds to a nano-light-shielding particle dispersion system under controlled temperature conditions, the compatibilizer molecules undergo condensation or strong adsorption with the hydroxyl groups on the surface of the nano-light-shielding particles via silane groups, simultaneously introducing an organic unsaturated structure onto the particle surface. This surface treatment method constructs an organic compatibility interface between the nano-light-shielding particles and the sulfur-rich polymer and silicon-oxygen framework structure, effectively reducing the tendency of particles to aggregate in high-solids systems. After centrifugation and redispersion with a double-boiling-point organic solvent, unbound surface compatibilizers and byproducts can be further removed, resulting in a nano-light-shielding particle dispersion with good stability and system compatibility.

[0040] S3.3. At 25-35℃, the dispersion of nano-shading particles is added to part of the pre-mixed solution and sheared and dispersed for 10-30 min. Then it is added back to the remaining pre-mixed solution. During the addition process, the stirring speed is controlled at 400-900 rpm and the system temperature is maintained at 25-35℃. After the addition is completed, stirring is continued for 30-60 min to obtain the dispersion mother liquor.

[0041] By employing a partial pre-dispersion and re-addition of the pre-mixed solution, nano-light-shielding particles are gradually introduced into the overall system, enabling a progressive distribution of the particles within the sulfur-rich polymer matrix and the silicon-oxygen framework. This segmented introduction and shear dispersion process effectively avoids the problems of excessively high local concentrations or abrupt viscosity changes caused by the one-time addition of nano-light-shielding particles. Simultaneously, under controlled temperature and stirring conditions, it promotes the formation of a stable interface between the organosilicon compatible layer on the particle surface and the matrix segments, thereby obtaining a uniformly dispersed and structurally stable dispersion mother liquor.

[0042] S3.4. Vacuum degassing treatment is performed on the dispersion mother liquor. The degassing temperature is controlled at 25-35℃, the vacuum degree is -0.08--0.095MPa, and the degassing time is 10-30min. Then, it is filtered through a solvent-resistant filter membrane of 0.45μm or 0.2μm. The filtration process is carried out in the dark and under closed conditions to obtain a precursor liquid containing surface-treated nano-light-shielding particles.

[0043] Vacuum degassing of the dispersion mother liquor removes microbubbles and dissolved gases introduced during mixing and shear dispersion, preventing them from forming optical defects or mechanical weaknesses in the micron-sized photoresist film. Subsequent fine filtration using a solvent-resistant membrane effectively removes trace aggregates and impurity particles, further improving the purity and uniformity of the system. The precursor solution obtained after degassing and filtration shows significant improvements in optical properties, rheological stability, and film formation consistency, providing a stable and reliable foundation for the subsequent introduction of the photoinitiation system and the formation of negative micron-sized photoresist.

[0044] S4. Add photoinitiating components and crosslinking promoting components to the precursor solution to obtain negative micron-sized photoresist.

[0045] By introducing photoinitiating and crosslinking promoting components into the precursor solution, a complete photoresponsive crosslinking system is constructed, transforming the precursor solution into a negative micron-sized photoresist with exposure curing capability. Under exposure conditions, the photoinitiating component efficiently generates free radicals, triggering polymerization reactions on unsaturated structures at the interface of sulfur-rich acrylate segments and surface-compatible nano-shading particles. The crosslinking promoting component, by providing multifunctional reaction sites, increases the crosslinking density and network integrity of the system, enabling the photoresist to form dense and dimensionally stable cured patterns even under micron-sized thick film conditions.

[0046] Step S4 includes: S4.1 Transfer the precursor solution to a sealed brown dispensing bottle and stir at 25–30°C for 10–20 min. Add the photoinitiator to the precursor solution under light-protected conditions and stir at 300–600 rpm at 25–35°C for 20–40 min. Add the crosslinking promoter while stirring continuously and adjust the stirring speed to 400–800 rpm. Continue stirring at 30–45°C for 30–60 min. The photoinitiator is selected from at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, benzophenone, and isopropylthionthrone. The crosslinking promoter includes at least one of trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and ethoxylated trimethylolpropane triacrylate.

[0047] By sequentially adding photoinitiating and crosslinking promoting components under light-protected and controlled temperature conditions, and employing a staged stirring method, various active components are uniformly dispersed and fully dissolved in the system. Photoinitiating components, such as hydroxyketones, phosphine oxides, and thioanthrone compounds, possess high photogenerated free radical efficiency and can synergistically interact with the sulfur-rich acrylate structure, improving the system's response sensitivity to exposure energy. Crosslinking promoting components, such as multifunctional acrylates, introduce high-density reaction sites, promoting the rapid construction of a three-dimensional crosslinked network. This step-by-step addition and temperature control method effectively avoids local enrichment or premature reaction of active components, enabling the negative micron-sized photoresist to maintain rheological stability while possessing uniform and controllable photocuring properties.

[0048] S4.2. Vacuum degassing is performed at 25–35℃, with the vacuum degree controlled at –0.08––0.095 MPa and the degassing time at 10–30 min. After degassing, the solution is filtered using a solvent-resistant filter membrane of 0.45 μm or 0.2 μm. The filtration process is carried out under light-proof and sealed conditions. After filtration, the filtrate is collected to obtain negative micron-sized photoresist.

[0049] Vacuum degassing of the mixture removes microbubbles and dissolved gases trapped during stirring and component introduction, preventing them from forming optical scattering centers or mechanical defects in the micron-sized photoresist film. Subsequent filtration using a solvent-resistant membrane effectively removes trace agglomerates and impurity particles, further improving the system's purity and uniformity. The negative micron-sized photoresist obtained after degassing and filtration exhibits significantly improved storage stability, film formation consistency, and exposure imaging quality, making it suitable for high-precision micron-sized photolithography processes.

[0050] This invention proposes a negative micron-sized photoresist, which is prepared by a method for preparing negative micron-sized photoresist.

[0051] Example 1: By weight, the sulfur-containing acrylate polymer is selected from 20 parts of poly-2-(phenylthio)ethyl acrylate; the double-boiling-point organic solvent is selected from 70 parts of propylene glycol methyl ether acetate / cyclohexanone compound solvent, wherein the mass ratio of propylene glycol methyl ether acetate to cyclohexanone is 6:4; the nano-light-shielding particles are selected from 2 parts of nano-titanium dioxide; the surface compatibilizer is selected from methacryloyloxypropyltrimethoxysilane, and its amount is 10% of the mass of nano-titanium dioxide; the silicon-oxygen framework structure functional component solution is introduced into 6 parts according to the effective functional component; the photoinitiating component is selected from 1.2 parts of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide; and the crosslinking promoting component is selected from 6 parts of trimethylolpropane triacrylate.

[0052] Following step S1, perform S1.1, placing poly(2-(phenylthio)ethyl acrylate) in a vacuum oven and drying it at 50°C and –0.09 MPa for 8 hours. Simultaneously, dehydrate the propylene glycol methyl ether acetate / cyclohexanone compound solvent and store it in a sealed brown bottle for later use. Perform S1.2, adding the compound solvent to a jacketed glass mixing vessel, adding deionized water, and starting mechanical stirring. Adjust the stirring speed to 600 rpm and stabilize the temperature at 30°C using a constant temperature water bath. Perform S1.3, adding poly(2-(phenylthio)ethyl acrylate) to the glass mixing vessel in three portions, stirring for 15 minutes after each addition, then raising the temperature to 50°C and continuing stirring for 60 minutes to obtain a sulfur-rich polymer matrix solution.

[0053] Following step S2, perform S2.1: Add 40 parts of a mixed solvent of anhydrous ethanol and toluene (mass ratio of anhydrous ethanol to toluene 1:1) to a three-necked flask. Purge with nitrogen and maintain the system temperature at 5°C. Then add 10 parts of a silane precursor (mass ratio of methyltriethoxysilane to phenyltriethoxysilane 7:3). While stirring at 450 rpm, add 1.5 parts of deionized water and 0.1 parts of glacial acetic acid to allow the silane precursor to undergo controlled hydrolysis and condensation reactions, forming a siloxane sol. Perform S2.2: Continue stirring for 2 hours under nitrogen protection, and slowly raise the temperature to 25°C to promote the formation of siloxane sols. 1.5 parts of methacryloxypropyltrimethoxysilane were added to the sol, and the reaction was continued with stirring for 4 hours. After the reaction was completed, rotary evaporation was performed to obtain a silicon-oxygen framework structure functional component solution. S2.3 was performed, and 10% of the sulfur-rich polymer matrix solution was taken as a pre-prepared mother liquor. The silicon-oxygen framework structure functional component solution was added to the pre-prepared mother liquor at 30°C and dispersed for 20 minutes. Then, it was added back to the remaining sulfur-rich polymer matrix solution dropwise. During the back addition, the stirring speed was 600 rpm and the system temperature was 30°C. After the back addition was completed, the temperature was raised to 45°C and stirring was continued for 45 minutes to obtain a pre-prepared mixture.

[0054] Following step S3, perform S3.1: Place nano-titanium dioxide in a vacuum oven and dry at 70℃ and –0.09MPa for 4 hours. Then add 20 parts of anhydrous ethanol and ultrasonically disperse for 10 minutes. Perform S3.2: Add methacryloyloxypropyltrimethoxysilane under continuous stirring and react at 60℃ for 2 hours. After the reaction, centrifuge and wash and redisperse three times with a propylene glycol methyl ether acetate / cyclohexanone compound solvent to obtain a nano-light-shielding particle dispersion. Perform S3.3: Add the nano-light-shielding particle dispersion to a portion of the pre-mixed solution at 30℃ and shear disperse for 20 minutes. Then add it back to the remaining pre-mixed solution. During the back addition, the stirring speed is 700 rpm, and stirring is continued for 45 minutes to obtain a dispersion mother liquor. Perform S3.4: Degas the dispersion mother liquor at 30℃ and –0.09MPa for 20 minutes, and then filter it through a 0.45μm solvent-resistant filter membrane to obtain the precursor solution.

[0055] Following step S4, perform S4.1: transfer the precursor solution to a sealed brown mixing bottle, stir at 28°C for 15 min, add the photoinitiator under light-protected conditions, and stir at 30°C and 500 rpm for 30 min. Then add the crosslinking promoter and adjust the stirring speed to 650 rpm, and continue stirring at 35°C for 45 min. Perform S4.2: degas at 30°C and –0.09 MPa for 20 min, and then filter through a 0.2 μm solvent-resistant filter membrane to obtain a negative micron-sized photoresist.

[0056] Example 2: Compared with Example 1, Example 2 uses 18 parts of poly(2,2′-thiodiethyl acrylate) and 4 parts of poly(thiodiethanol diacrylate) as the sulfur-containing acrylate polymer; 68 parts of a compound solvent of γ-butyrolactone / methyl isobutyl ketone with a mass ratio of 6:4 as the double-boiling-point organic solvent; 1.5 parts of nano-zinc oxide particles; 8 parts of the silicon-oxygen framework structural functional component; 1.0 part of 1-hydroxycyclohexylphenyl ketone as the photoinitiator; and 5 parts of pentaerythritol tetraacrylate and 2 parts of ethoxylated trimethylolpropane triacrylate as the crosslinking promoter. The pre-mixed solution obtained in S2.4 is transferred to a sealed stirring container under light-protected conditions and incubated at 35°C. An amine-based acid-scavenging stabilizer is added. This stabilizer includes at least one of triethylamine, diisopropylethylamine, and pyridine. In this embodiment, triethylamine is used. The amount of the stabilizer added is 0.05 to 2 parts by weight relative to the solid content in the sulfur-rich polymer matrix solution. In this embodiment, 0.1 parts are added. The mixture is stirred at 600 rpm for 30 minutes to neutralize any trace acidic residues in the pre-mixed solution and create a buffer environment. The system is then maintained at 35°C and allowed to stand for 20 minutes to allow the silicon-oxygen framework functional components and the sulfur-rich polymer matrix to undergo interfacial rearrangement, resulting in a stable pre-mixed solution suitable for introducing nano-zinc oxide. The process conditions for the remaining steps S1 to S4 are the same as in Example 1, yielding a negative micron-sized photoresist.

[0057] Example 3: Compared with Example 1, Example 3 uses 16 parts of poly(phenylthio)ethyl acrylate and 6 parts of poly(2,2′-thiodiethyl acrylate) as the sulfur-containing acrylate polymer; 65 parts of dimethyl sulfoxide / cyclopentanone compound solvent with a mass ratio of 5:5 as the double-boiling-point organic solvent; 2.5 parts of nano-cerium oxide particles; vinyltriethoxysilane as the surface compatibilizer, with an amount of 12% of the mass of nano-titanium dioxide; 10 parts of silicon-oxygen framework structural functional component; 0.2 parts of isopropylthionthrone and 0.8 parts of benzophenone as the photoinitiating component; and 7 parts of ethoxylated trimethylolpropane triacrylate as the crosslinking promoting component. In step S3.2, a weakly coordinating site-occupying component was first added to the nano-cerium oxide dispersion at 55°C and stirred at 500 rpm for 30 min to allow it to preferentially coordinate reversibly with the strong adsorption sites on the cerium oxide surface and form a transient site-occupying layer. Then, a surface compatibilizer was added, and the reaction was continued at 70°C for 3 h to allow the surface compatibilizer to form a more uniform surface film under the guidance of the site-occupying layer. After the reaction, centrifugation, washing, and redispersion were performed according to step S3.2. The remaining steps were the same as in Example 1, yielding a negative micron-sized photoresist. The weakly coordinating site-occupying component included at least one of acetylacetone, dibenzoylmethane, trifluoroacetylacetone, benzoic acid, p-methylbenzoic acid, salicylic acid, diethyl ethylphosphonate, dimethyl methylphosphonate, and diethyl phenylphosphonate. In this example, the weakly coordinating site-occupying component was acetylacetone, and the amount added was 0.5%–5% of the mass of the nano-cerium oxide. In this example, 2% was added.

[0058] Comparative Example 1: Compared with Example 1, Comparative Example 1 only omitted step S2 and did not introduce functional components with silicon-oxygen framework structures. The compound names, dosage ratios, and process conditions of the remaining steps S1, S3, and S4 were the same as those in Example 1.

[0059] Comparative Example 2: Compared with Example 1, Comparative Example 2 only omits the addition of a surface compatibilizer in step S3.2. After drying and ultrasonic dispersion with anhydrous ethanol, the nano-titanium dioxide is directly centrifuged and washed and redispersed using a propylene glycol methyl ether acetate / cyclohexanone compound solvent. The remaining steps are the same as in Example 1.

[0060] Experimental procedure: Experiments on the viscosity of the photoresist (25℃, mPa·s) and the 7-day viscosity change rate (%). The negative micron-sized photoresists prepared in each example and comparative example were thoroughly mixed under light-protected conditions, and samples were placed in a constant temperature environment of 25℃ for 30 minutes to eliminate temperature gradients. Viscosity was measured using a rotational rheometer or a Brookfield viscometer, selecting a rotor and rotational speed matching the sample viscosity range, and recording stable readings as the "25℃ photoresist viscosity". Subsequently, the same batch of photoresist was dispensed into sealed brown bottles and stored at 25℃ under light-protected conditions for 7 days without additional stirring. After the storage period, the viscosity was measured again under the same test conditions. The 7-day viscosity change rate was calculated as "(7-day viscosity - initial viscosity) / initial viscosity × 100%" to reflect the storage stability of the photoresist and the degree of systemic drift.

[0061] Experiment on dispersion stability (7-day sedimentation height / total height, %). Take 20 mL of each gel sample and place them into transparent graduated centrifuge tubes or glass graduated cylinders of the same specifications. Seal and protect from light, and let stand at 25℃ for 7 days. After standing, without shaking the samples, directly observe and read the height of the "visible sedimentation layer or clear layer" in the sample. Calculate "(height of non-uniform sedimentation layer / total liquid column height) × 100%" to obtain the dispersion stability index. The higher the index, the less likely the light-shielding nanoparticles are to agglomerate and settle in the system constructed by the sulfur-rich polymer matrix solution and the functional components of the silicon-oxygen framework structure.

[0062] Experiments were conducted to assess the first-pass yield (%) of the 0.2 μm filter membrane. Each adhesive solution was restored to 25–30°C under light-protected conditions, and filtration tests were performed using a solvent-resistant filtration device (PTFE or nylon filter membrane). A fixed volume (e.g., 100 mL each time) of the adhesive solution was filtered through a 0.2 μm solvent-resistant filter membrane under constant pressure difference or constant flow rate. The occurrence of significant membrane clogging, a sharp drop in flow rate, or the need to replace the filter membrane was recorded during each filtration process. The same formulation was repeated several times (e.g., 10 times), and the first-pass yield was calculated based on the percentage of times the filter membrane did not need to be replaced and the filtration process remained stable. This process was used to evaluate the impact of particle agglomeration, microgels, and impurities on the precision filtration process.

[0063] Experiments on the thickness-direction light intensity uniformity index (%): Various adhesive solutions were applied to the same substrate (e.g., glass or silicon wafer) using the same method (e.g., spin coating, blade coating, or constant thickness coater). The target thickness (e.g., 20–50 μm) was obtained by controlling the coating gap or spin coating parameters. The films were then dried under identical conditions to allow solvent evaporation, forming uniform thick films. Thickness was confirmed by measuring at multiple points using a profilometer or film thickness gauge and averaging the measurements. Subsequently, a UV-Vis spectrophotometer or integrating sphere accessory was used to measure the transmittance of the thick film sample at the target exposure wavelength, or the equivalent light energy attenuation difference between the upper and lower surfaces was measured using a two-sided incidence method. The equivalent transmittance / attenuation uniformity at different depths of the thick film was converted into a percentage and defined as the thickness-direction light intensity uniformity index. This index reflects the uniformity of the modulation of light propagation along the thickness direction by the nano-shading particles and the functional components of the silicon-oxygen framework structure.

[0064] Experiments were conducted on the perpendicularity (°) of the sidewalls of micron-sized patterns. After depositing various adhesive solutions onto silicon or glass wafers to a predetermined thickness, the samples were exposed to ultraviolet light using a mask to form microstructures characterizing the sidewall morphology. No further development was required after exposure; only the stable micron-sized structure was needed. The resulting micron-sized sample was cross-sectionally prepared (using cutting or ion beam polishing). The cross-sectional morphology was observed using a scanning electron microscope. The angle between the sidewall and the substrate normal was measured, and the average value at multiple locations was taken to obtain the sidewall perpendicularity. This indicator reflects the influence of light energy distribution and cross-linking uniformity on the quality of the structural sidewalls in thick-film systems.

[0065] Regarding the density of defects within the membrane (numbers / cm²) 2 The experiment involved preparing standard thick film samples of each adhesive solution, drying and setting them, and then using an optical microscope or surface defect detection system at the same magnification to perform multi-field scanning on a specified area (e.g., 1 cm²). The number of visible defects (including particle agglomerations, pinholes, residual bubbles, gel particles, etc.) was counted and converted into defect density per unit area. At least several different fields of view were taken from each sample and averaged to reduce random errors. This index is used to evaluate the overall effect of "whether the surface compatibilizer forms a sufficient film, whether the silicon-oxygen framework structure provides a stable matrix, and whether degassing and filtration are effective" on defect control.

[0066] The experimental data for the above experiments are shown in Table 1.

[0067] Table 1:

[0068] As can be seen from Comparative Example 1, without performing step S2 and without introducing a silicon-oxygen framework functional component, the 7-day viscosity change rate of the adhesive solution significantly increased, the dispersion stability decreased, and the single-pass yield of the filter membrane significantly decreased. Simultaneously, the uniformity of light intensity along the thickness direction and the perpendicularity of the sidewalls decreased, while the defect density within the membrane increased. This indicates that without a silicon-oxygen framework functional component, the sulfur-rich polymer matrix struggles to form a stable supporting and interfacial buffer network for the nano-shading particles and the photoinitiation system, leading to poor particle dispersion and microscopic uniformity of the system. Uneven light energy distribution and crosslinking gradients are more likely to occur within the thick film, thereby increasing surface and internal defects and weakening film formation consistency.

[0069] As can be seen from Comparative Example 2, when no surface compatibilizer is added in step S3.2, the initial viscosity of the adhesive solution is relatively high and the viscosity change rate over 7 days is further increased. The dispersion stability and the first-pass yield of the filter membrane are significantly reduced, the defect density is the highest, and the adhesion grade is worse. This indicates that the surface compatibilizer plays a key role in your preparation method: by forming an interfacial layer on the surface of the nano-light-shielding particles that is compatible with the sulfur-rich polymer matrix and the functional components of the silicon-oxygen framework structure, it inhibits particle bridging and agglomeration and microgel formation, reduces the risk of filter blockage, and reduces particle agglomeration defects within the membrane, thereby improving the sidewall verticality and overall quality stability of the thick film pattern.

[0070] Examples 1-3 all followed step S2 and added a surface compatibilizer in S3.2. Overall, they exhibited lower viscosity change rate, higher dispersion stability, and higher single-pass filter membrane throughput. Simultaneously, they showed higher light intensity uniformity index in the thickness direction, lower defect density, and adhesion reaching grade 0. This indicates that the combined process of sulfur-rich polymer matrix solution, silicon-oxygen framework functional components, surface-compatible nano-shading particles, and photoinitiation and crosslinking promotion can synergistically improve light energy transfer and crosslinking uniformity in thick film systems. Furthermore, Example 2, by adding an acid-trapping buffer environment before introducing nano-zinc oxide, suppressed the sensitivity of zinc oxide to trace acid residues, maintaining high levels of dispersion stability and filtration performance. Example 3, by introducing a weak coordination site-occupying step into the nano-cerium oxide system, made silane film formation more uniform and reduced the bridging and agglomeration tendency caused by strong adsorption on the cerium oxide surface. Therefore, it showed better performance in terms of light intensity uniformity index and defect density in the thickness direction, demonstrating that improved adaptability to different shading particles can lead to more stable and controllable preparation results.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a negative micron-sized photoresist, characterized in that the steps include... include: S1. Add sulfur-containing acrylate polymers to a double-boiling-point organic solvent and dissolve them completely under stirring to form a sulfur-rich polymer matrix solution. S2. Add functional components with a silicon-oxygen framework structure to the sulfur-rich polymer matrix solution to obtain a pre-mixed solution; S3. Add surface-treated nano-light-shielding particles to the pre-mixed liquid, and then stir and vacuum degas to obtain the precursor liquid. S4. Add photoinitiating components and crosslinking promoting components to the precursor solution to obtain negative micron-sized photoresist.

2. The method for preparing a negative micron-sized photoresist according to claim 1, characterized in that, Step S1 includes: S1.1 Place the sulfur-containing acrylate polymer in a vacuum oven and dry it at 40-60℃ and -0.08--0.095MPa for 4-12 hours. At the same time, pre-dehydrate the double-boiling-point organic solvent and store it in a sealed brown bottle for later use. S1.2 Add the double-boiling-point organic solvent to the jacketed glass mixing vessel, add deionized water, turn on the mechanical stirrer and adjust the stirring speed to 300-800 rpm, and stabilize the temperature at 25-35℃ through a constant temperature water bath. S1.

3. Add the acrylate polymer containing sulfur structural units to the glass mixing vessel in multiple stages. After each addition, maintain stirring for 10 to 20 minutes. Then raise the temperature to 45 to 55°C and continue stirring for 30 to 90 minutes to obtain a sulfur-rich polymer matrix solution.

3. The method for preparing a negative micron-sized photoresist according to claim 1 or 2, characterized in that, In step S1, the sulfur-containing acrylate polymer includes at least one of poly(phenylthio)ethyl acrylate, poly(2,2′-thiodiethyl acrylate), and poly(thiodiethanol diacrylate), and the double-boiling-point organic solvent includes at least one of propylene glycol methyl ether acetate / cyclohexanone composite solvent, γ-butyrolactone / methyl isobutyl ketone composite solvent, N-methylpyrrolidone / propylene glycol methyl ether composite solvent, and dimethyl sulfoxide / cyclopentanone composite solvent.

4. The method for preparing a negative micron-sized photoresist according to claim 1, characterized in that, Step S2 includes: S2.1 Add a mixture of anhydrous ethanol and toluene to a three-necked flask, purge with nitrogen for protection and control the system temperature at 0-10℃. Then add the silane precursor to the three-necked flask, and add deionized water and an acidic catalyst at a stirring speed of 300-600 rpm to allow the silane precursor to undergo controlled hydrolysis and condensation reactions to form a siloxane sol. S2.2 Continue stirring the silica-oxygen structure sol under nitrogen protection for 1-4 hours, and slowly raise the temperature to 20-30℃. Add an organosilane modifier containing unsaturated bonds to the silica-oxygen structure sol and continue stirring for 2-6 hours. After the reaction is completed, perform vacuum distillation or rotary evaporation to obtain a silica-oxygen framework structure functional component solution. S2.

3. The silicon-oxygen framework structure functional component solution is dehydrated and stabilized, then transferred to a sealed brown container for storage in the dark. A portion of the sulfur-rich polymer matrix solution is taken as the pre-prepared mother liquor. The silicon-oxygen framework structure functional component solution is added to the pre-prepared mother liquor at 25-35°C and dispersed for 10-30 minutes. The pre-prepared mother liquor is then added back to the remaining sulfur-rich polymer matrix solution dropwise. During the back-addition process, the stirring speed is controlled at 400-900 rpm and the system temperature is maintained at 25-35°C. After the back-addition is completed, the temperature is slowly raised to 40-50°C and stirring is continued for 30-60 minutes to obtain the pre-prepared mixture.

5. The method for preparing a negative micron-sized photoresist according to claim 4, characterized in that, In step S2, the silane precursor includes at least one of methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, hydrotriethoxysilane, and phenyltriethoxysilane; the organosilane modifier includes at least one of methacryloxypropyltrimethoxysilane, acryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and allyltrimethoxysilane; and the acid catalyst includes at least one of glacial acetic acid, dilute hydrochloric acid, dilute nitric acid, oxalic acid, and p-toluenesulfonic acid.

6. The method for preparing a negative micron-sized photoresist according to claim 1, characterized in that, Step S3 includes: S3.1 Place the nano-light-shielding particles in a vacuum oven and dry them at 60-90℃ and -0.08--0.095MPa for 2-6 hours. Add the dried nano-light-shielding particles to anhydrous ethanol and disperse them by ultrasonication for 5-15 minutes. S3.2 Add a surface compatibilizer to the nano-light-shielding particles under continuous stirring, and react at 40-70℃ for 1-4 hours. After the reaction is completed, centrifuge the surface-treated nano-light-shielding particles, and wash and redisperse them with a double-boiling-point organic solvent to obtain a nano-light-shielding particle dispersion. S3.

3. At 25-35℃, the dispersion of nano-shading particles is added to part of the pre-mixed solution and sheared and dispersed for 10-30 min. Then it is added back to the remaining pre-mixed solution. During the addition process, the stirring speed is controlled at 400-900 rpm and the system temperature is maintained at 25-35℃. After the addition is completed, stirring is continued for 30-60 min to obtain the dispersion mother liquor. S3.

4. Vacuum degassing treatment is performed on the dispersion mother liquor. The degassing temperature is controlled at 25-35℃, the vacuum degree is -0.08--0.095MPa, and the degassing time is 10-30min. Then, it is filtered through a solvent-resistant filter membrane of 0.45μm or 0.2μm. The filtration process is carried out in the dark and under closed conditions to obtain a precursor liquid containing surface-treated nano-light-shielding particles.

7. The method for preparing a negative micron-sized photoresist according to claim 6, characterized in that, In step S3, the surface compatibilizer includes at least one of methacryloyloxypropyltrimethoxysilane, acryloyloxypropyltriethoxysilane, vinyltriethoxysilane, and allyltrimethoxysilane; the double-boiling-point organic solvent includes at least one of propylene glycol methyl ether acetate / cyclohexanone composite solvent, γ-butyrolactone / methyl isobutyl ketone composite solvent, N-methylpyrrolidone / propylene glycol methyl ether composite solvent, and dimethyl sulfoxide / cyclopentanone composite solvent; and the nano-light-shielding particles include at least one of nano-titanium dioxide particles, nano-zinc oxide particles, and nano-cerium oxide particles.

8. The method for preparing a negative micron-sized photoresist according to claim 1, characterized in that, Step S4 includes: S4.1 Transfer the precursor solution to a sealed brown mixing bottle and stir at 25-30°C for 10-20 min. Add the photoinitiating component to the precursor solution under light-protected conditions and stir at 300-600 rpm at 25-35°C for 20-40 min. Add the crosslinking promoting component while stirring continuously, and adjust the stirring speed to 400-800 rpm. Continue stirring at 30-45°C for 30-60 min. S4.

2. Vacuum degassing is performed at 25–35℃, with the vacuum degree controlled at –0.08––0.095 MPa and the degassing time at 10–30 min. After degassing, the solution is filtered using a solvent-resistant filter membrane of 0.45 μm or 0.2 μm. The filtration process is carried out under light-proof and sealed conditions. After filtration, the filtrate is collected to obtain negative micron-sized photoresist.

9. A method for preparing a negative micron-sized photoresist according to claim 1 or 8, characterized in that, In step S4, the photoinitiating component is selected from at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, benzophenone, and isopropylthionthrone, and the crosslinking promoting component includes at least one of trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and ethoxylated trimethylolpropane triacrylate.

10. A negative micron-scale photoresist, characterized in that, It is prepared by a method for preparing a negative micron-sized photoresist as described in any one of claims 1-9.

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