A volatile solvent-free photoresist and preparation method thereof

Abstract

The present invention relates to the technical field of photoresists, and in particular to a volatile solvent-free photoresist and a preparation method thereof. The present invention overcomes the problem of poor stability of current photoresists. The synthetic raw materials of the photoresist of the present invention include a composite resin, a modified photoinitiator, a composite cross-linking agent, a modified curing agent, fluorinated silicone nanoparticles, polyimide microspheres and a composite dispersant; the above materials are stirred and ultrasonically mixed to obtain a precursor solution, and then degassing is performed to obtain the photoresist. The present invention adjusts the viscosity by introducing a monofunctional resin into the multifunctional resin, and synergistically improves the adhesion of the photoresist with the modified photoinitiator; the prepared modified curing agent and composite cross-linking agent are added to the photoresist to improve its tensile strength; the acid and alkali resistance of the photoresist is improved by adding the prepared fluorinated silicone nanoparticles and polyimide microspheres; and the uniformity of the photoresist is improved by controlling the amount of the composite dispersant and the time of ultrasonic stirring.

Description

Technical Field

[0001] The invention relates to the technical field of photoresists, in particular to a photoresist without volatile solvents and a preparation method thereof. Background Art

[0002] Photoresist is a core material in the manufacture of semiconductor devices such as chips and integrated circuits. It is used to transfer designed circuit patterns onto semiconductor wafers. As chip integration continues to increase, the requirements for photoresist performance, such as resolution, sensitivity, and corrosion resistance, are becoming increasingly stringent, driving continuous innovation in photoresist technology.

[0003] Negative photoresist is a key material in the photolithography process. After exposure, the unexposed areas can be dissolved and removed by the developer, while the exposed areas are retained due to reactions such as cross-linking, thus forming the desired pattern on the substrate. Negative photoresist often uses a macromolecular resin as the main resin. Due to uneven molecular weight distribution and composition differences of the resin, the uniformity is low, resulting in poor stability of the photoresist. In addition, macromolecular resins generally have a large molecular weight and low resolution, making it difficult to ensure photocuring sensitivity and development speed. However, the use of small molecule resins is costly to process, requiring control of their purity during the synthesis process, and is relatively expensive. More importantly, small molecule resins are difficult to prepare as high-viscosity liquids, which can easily cause the photoresist to peel and disappear, thus affecting the quality of the entire semiconductor device.

[0004] Currently, most widely used negative photoresists are solvent-based, and the solvents are volatile. These volatile solvents are highly toxic and flammable, requiring specialized equipment for both production and use to ensure safety. Furthermore, volatile solvents are removed during use, rather than remaining part of the photoresist during the photolithography process. This increases costs and poses long-term risks to both workers and the environment, hindering sustainable economic and environmental development.

[0005] To sum up, today's negative photoresist still has shortcomings such as high shrinkage and poor adhesion, which leads to poor stability of the photoresist, and volatile solvents pose certain safety hazards during the production process. Therefore, it is urgent to solve the above problems.

[0006] Therefore, a volatile solvent-free photoresist and a preparation method thereof are proposed. Summary of the Invention

[0007] The purpose of the present invention is to design a volatile solvent-free photoresist and a preparation method thereof. The synthetic raw materials of the present invention include a composite resin, a modified photoinitiator, a composite crosslinking agent, a modified curing agent, fluorinated silicone nanoparticles, polyimide microspheres, and a composite dispersant; the above materials are stirred and ultrasonically mixed to obtain a precursor solution, which is then degassed to obtain the photoresist. The present invention adjusts the viscosity by introducing a monofunctional resin into the multifunctional resin, and prepares a modified photoinitiator to improve the adhesion of the photoresist; the tensile strength of the photoresist is improved and the shrinkage rate is reduced by preparing a modified curing agent and adding it to the photoresist with the composite crosslinking agent; the acid and alkali resistance and adhesion of the photoresist are improved by adding the prepared fluorinated silicone nanoparticles and polyimide microspheres; and the uniformity of the photoresist is improved by controlling the amount of the composite dispersant and the time of ultrasonic stirring.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] In one aspect, the present invention provides a method for preparing a volatile solvent-free photoresist, which comprises the following steps, in parts by weight:

[0010] S1: 40-60 parts of the composite resin are added to a reaction vessel, and 5-9 parts of the modified photoinitiator are slowly added at a rotation speed of 500 rpm, and the mixture is stirred for 1 h to 2 h to form a uniform mixed solution;

[0011] S2: 1-3 parts of a composite crosslinking agent, 0.5-0.9 parts of a modified curing agent, 0.1-0.5 parts of fluorinated silicone nanoparticles, 0.1-0.3 parts of polyimide microspheres, and 0.2-0.4 parts of a composite dispersant are added one by one to the mixed solution at a rotation speed of 500 rpm, ultrasonicated at 20 kHz for 10 min-30 min in an ultrasonic machine, and then stirred at 800 rpm for 2 h-4 h to obtain a photoresist precursor solution;

[0012] S3 degasses the photoresist precursor solution, evacuates the reaction container to a vacuum state, and slowly stirs the solution at a rotation speed of 50 rpm for 20-60 minutes to eliminate bubbles. After the treatment, a photoresist is obtained.

[0013] Preferably, the preparation method of the composite resin is as follows: 19-24 parts of pentaerythritol triacrylate are added to a three-necked flask, followed by slowly adding 8 parts of isobornyl acrylate, while turning on the agitator and setting the stirring speed to 300 rpm, placing the three-necked flask in a constant temperature water bath, controlling the temperature at 60°C, and continuing to stir for 90 minutes to obtain a mixture; while stirring, slowly adding 0.1 parts of p-hydroxyanisole to the mixture, and continuing to stir for 60 minutes to obtain a composite resin.

[0014] Preferably, the preparation method of the modified photoinitiator is as follows: 8-12 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 10 parts of toluene are added to a reactor, stirred for 30 minutes, and then 1 part of ethylenediamine and 0.2 parts of triethylamine are added, the reaction system is heated to 80°C, and stirred for 8 hours under heating conditions. After the reaction is completed, the reaction solution is cooled to room temperature, the organic solvent is removed by distillation, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain the modified photoinitiator.

[0015] Preferably, the composite crosslinking agent is a mixture of γ-methacryloxypropyltrimethoxysilane and hexamethoxymethylmelamine, and the weight ratio of γ-methacryloxypropyltrimethoxysilane to hexamethoxymethylmelamine is 1-5:1.

[0016] Preferably, the preparation method of the modified curing agent is as follows: 3-7 parts of benzoin dimethyl ether and 20 parts of anhydrous ethanol are placed in a flask and stirred at room temperature for 30 minutes to form a transparent solution; 2 parts of β-cyclodextrin and 20 parts of deionized water are placed in another flask and stirred at 60°C for 40 minutes to form a clear solution; under continuous stirring and at 60°C, the transparent solution is slowly added dropwise to the clear solution at a rate of 2 drops per second. After the addition is complete, the stirring reaction is continued at 60°C for 2 hours to 6 hours to obtain a reaction solution; the reaction solution is naturally cooled to room temperature, and then refrigerated and allowed to stand at 4°C for 12 hours; after the standing period, the reaction solution is centrifuged at 4000 rpm for 15 minutes to separate the precipitate, the precipitate is washed 5 times with deionized water, and then the precipitate is placed in a vacuum drying oven and dried at 50°C for 24 hours to obtain the modified curing agent.

[0017] Preferably, the preparation method of fluorinated silicone nanoparticles is as follows: 1 part of heptafluorodecyltrimethoxysilane and 1-5 parts of ethyl orthosilicate are mixed, followed by adding 10 parts of ethanol and stirring for 60 minutes to obtain a mixed solution A; 1 part of a 0.1 mol / L ammonia solution is slowly added dropwise to the mixed solution A, and stirring is continued for 2 hours to 4 hours. After the reaction is completed, the mixed solution A is allowed to stand and age for 2 hours, and then the precipitate is washed out by centrifugation, and the precipitate is vacuum dried at 60°C for 12 hours to obtain fluorinated silicone nanoparticles.

[0018] Preferably, the preparation method of polyimide microspheres is as follows: dissolving 1-3 parts of pyromellitic dianhydride in 5 parts of N,N-dimethylformamide to obtain solution A; dissolving 3 parts of 4,4'-diaminodiphenyl ether in 5 parts of N,N-dimethylformamide to obtain solution B; slowly adding solution A dropwise to solution B to form a prepolymer solution; then adding 0.2 parts of sodium lauryl sulfate to the prepolymer solution, and continuing to stir for 30 minutes to form a stable emulsion; adding 0.1 parts of potassium persulfate to the emulsion, stirring for 1 hour, and then reacting at 100°C for 4-8 hours. After the reaction is completed, the precipitate is centrifuged and washed, and finally dried in a vacuum drying oven at 60°C for 12 hours to obtain polyimide microspheres.

[0019] Preferably, the composite dispersant is a mixture of fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate, and the weight ratio of fatty alcohol polyoxyethylene ether to sodium dodecylbenzenesulfonate is 1-3:2.

[0020] Another aspect of the present invention provides a volatile solvent-free photoresist, wherein the synthetic raw materials of the photoresist include a composite resin, a modified photoinitiator, a composite cross-linking agent, a modified curing agent, fluorinated silicone nanoparticles, polyimide microspheres and a composite dispersant;

[0021] Composite resins include pentaerythritol triacrylate and isobornyl acrylate;

[0022] Modified photoinitiators include ethyl 2,4,6-trimethylbenzoylphenylphosphonate and ethylenediamine;

[0023] Modified curing agents include benzoin dimethyl ether and β-cyclodextrin;

[0024] Fluorosilicone nanoparticles include heptadecafluorodecyltrimethoxysilane and ethyl orthosilicate;

[0025] The polyimide microspheres include pyromellitic dianhydride and 4,4'-diaminodiphenyl ether.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention introduces a monofunctional resin into a multifunctional resin to adjust viscosity and prepares a modified photoinitiator to improve the adhesion of the photoresist. Pentaerythritol triacrylate provides a high crosslink density while balancing fluidity and curing speed. Isobornyl acrylate adjusts the system viscosity, facilitating uniform coating in the later stage. The two are combined to form a composite resin, in which the carboxyl groups undergo an esterification reaction with the silanol groups in the substrate material to form stable ester bonds, thereby firmly attaching the photoresist to the substrate and significantly enhancing the adhesion between the photoresist and the substrate. The modified photoinitiator, which incorporates amino groups, has higher photoinitiation efficiency and can rapidly generate a large number of active species such as free radicals or cations under illumination. These active species not only trigger crosslinking reactions within the composite resin itself but also promote crosslinking between the composite resin and other components in the photoresist, thereby enhancing the overall cohesion and adhesion of the photoresist to the substrate, thereby improving the stability of the photoresist. By comparison, photoresists using volatile solvents have poorer adhesion and fail to effectively improve the stability of the photoresist.

[0028] 2. The present invention improves the tensile strength and reduces shrinkage of photoresists by preparing a modified curing agent and adding it to the photoresist with a composite crosslinking agent. Benzoin dimethyl ether and β-cyclodextrin are combined to form a modified curing agent, which chemically reacts with the composite resin to form a more stable, uniform, and dense three-dimensional crosslinked network, thereby improving the tensile strength of the photoresist. The modified curing agent also reduces the internal stress generated by rapid molecular crosslinking, thereby reducing the shrinkage of the photoresist. The modified curing agent provides a suitable environment and conditions for the reaction of the composite crosslinking agent, which further strengthens and expands the crosslinked network formed by the modified curing agent, thereby improving the tensile strength of the photoresist. Regarding shrinkage reduction, the modified curing agent reduces shrinkage by controlling the reaction rate and compensating for shrinkage, while the composite crosslinking agent reduces shrinkage by forming a flexible structure and dispersing stress, thereby improving the stability of the photoresist.

[0029] 3. The present invention improves the acid and alkali resistance of the photoresist by adding prepared fluorinated silicone nanoparticles and polyimide microspheres. The fluorine atoms in the fluorinated silicone nanoparticles have extremely high electronegativity, forming C-F bonds with high bond energy and good chemical stability. This property makes the nanoparticles themselves highly resistant to acids and alkalis, thereby protecting the main structure of the photoresist from acid and alkali erosion. The polyimide microspheres form a physical barrier network in the photoresist. Acid or alkali molecules are blocked by the microspheres during diffusion, increasing the path and difficulty of their diffusion in the photoresist and reducing the speed and degree of acid and alkali erosion of the photoresist. The nanoparticles provide a chemically stable barrier at the microscopic level, while the microspheres form a physical barrier network at the macroscopic level. This composite structure can resist acid and alkali erosion from different scales and angles, further improving the acid and alkali resistance of the photoresist and enhancing the stability of the photoresist.

[0030] 4. The present invention improves the uniformity of the photoresist by controlling the amount of the composite dispersant used and the duration of ultrasonic stirring. The composite dispersant can reduce the surface tension between the components in the photoresist, allowing the components to be evenly dispersed in the system. In the photoresist, the composite dispersant molecules will adsorb on the surface of the solid particles, forming a protective film that keeps the particles at a certain distance from each other and maintains the dispersed state. During the synthesis of the photoresist, the force of ultrasound can break up the agglomeration structure between the various particles in the photoresist, dispersing large particles into small particles, thereby helping to improve the uniformity of the photoresist. The shear force generated during the stirring process can also disperse larger particle agglomerates to a certain extent, helping to improve the ultrasonic dispersion effect, thereby improving the stability of the photoresist. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Graphs showing the uniformity of the photoresists of Example 21 and Comparative Examples 17-21 of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Specific reference Figure 1 The present invention provides a volatile solvent-free photoresist and a preparation method thereof, and the technical solution is as follows:

[0034] Example 1

[0035] Preparation of composite resin:

[0036] 19 parts of pentaerythritol triacrylate were added to a three-necked flask, followed by the slow addition of 8 parts of isobornyl acrylate. At the same time, the agitator was turned on and the stirring speed was set to 300 rpm. The three-necked flask was placed in a constant temperature water bath, the temperature was controlled at 60°C, and stirring was continued for 90 minutes to obtain a mixture. Under stirring, 0.1 parts of p-hydroxyanisole was slowly added to the mixture, and stirring was continued for 60 minutes to obtain a composite resin.

[0037] Preparation of modified photoinitiator:

[0038] 8 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 10 parts of toluene were added to the reactor, and after stirring for 30 minutes, 1 part of ethylenediamine and 0.2 parts of triethylamine were added. The reaction system was heated to 80°C and stirred for 8 hours under heating conditions. After the reaction was completed, the reaction solution was cooled to room temperature, the organic solvent was removed by distillation, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain a modified photoinitiator.

[0039] Preparation of modified curing agent:

[0040] 3 parts of benzoin dimethyl ether and 20 parts of anhydrous ethanol were placed in a flask and stirred at room temperature for 30 minutes to form a transparent solution; 2 parts of β-cyclodextrin and 20 parts of deionized water were placed in another flask and stirred at 60°C for 40 minutes to form a clear solution; under continuous stirring and at 60°C, the transparent solution was slowly added dropwise to the clear solution, with the dropping speed controlled at 2 drops per second. After the dropwise addition was completed, the stirring reaction was continued at 60°C for 2 hours to obtain a reaction solution; the reaction solution was naturally cooled to room temperature, and then refrigerated and allowed to stand at 4°C for 12 hours; after the standing period, the reaction solution was centrifuged at 4000 rpm for 15 minutes to separate the precipitate, and the precipitate was washed with deionized water 5 times. Then, the precipitate was placed in a vacuum drying oven and dried at 50°C for 24 hours to obtain a modified curing agent.

[0041] Preparation of fluorinated silicone nanoparticles:

[0042] 1 part of heptafluorodecyltrimethoxysilane and 1 part of ethyl orthosilicate were mixed, followed by adding 10 parts of ethanol and stirring for 60 minutes to obtain a mixed solution A; 1 part of a 0.1 mol / L ammonia solution was slowly added dropwise to the mixed solution A, and stirring was continued for 2 hours. After the reaction was completed, the mixed solution A was allowed to stand and age for 2 hours, and then the precipitate was washed out by centrifugation, and the precipitate was vacuum dried at 60°C for 12 hours to obtain fluorinated silicone nanoparticles.

[0043] Preparation of polyimide microspheres:

[0044] 1 part of pyromellitic dianhydride was dissolved in 5 parts of N,N-dimethylformamide to obtain solution A; 3 parts of 4,4'-diaminodiphenyl ether were dissolved in 5 parts of N,N-dimethylformamide to obtain solution B; solution A was slowly added dropwise to solution B to form a prepolymer solution; then 0.2 parts of sodium lauryl sulfate was added to the prepolymer solution, and stirring was continued for 30 minutes to form a stable emulsion; 0.1 parts of potassium persulfate was added to the emulsion, stirred for 1 hour, and then reacted at 100°C for 4 hours. After the reaction, the precipitate was centrifuged and washed, and finally dried in a vacuum drying oven at 60°C for 12 hours to obtain polyimide microspheres.

[0045] Prepare photoresist:

[0046] S1: 40 parts of the composite resin was added to a reaction vessel, and 5 parts of the modified photoinitiator was slowly added at a rotation speed of 500 rpm, and the mixture was stirred for 1 hour to form a uniform mixed solution;

[0047] S2: 1 part of a composite crosslinking agent, 0.5 parts of a modified curing agent, 0.1 parts of fluorinated silicone nanoparticles, 0.1 parts of polyimide microspheres, and 0.2 parts of a composite dispersant are added one by one to the mixed solution at a rotation speed of 500 rpm, ultrasonicated at 20 kHz for 10 minutes in an ultrasonic machine, and then stirred at 800 rpm for 2 hours to obtain a photoresist precursor solution;

[0048] S3 degasses the photoresist precursor solution, evacuates the reaction container to a vacuum state, and slowly stirs the solution at a rotation speed of 50 rpm for 20 minutes to eliminate bubbles. After the treatment, a photoresist is obtained.

[0049] Examples 2-6 refer to the parameter conditions in Example 1, and the specific differences are shown in Table 1.

[0050] Comparative Example 1 refers to the parameter conditions in Example 1, except that only pentaerythritol triacrylate is used as the base resin.

[0051] Comparative Example 2 refers to the parameter conditions in Example 1, except that only isobornyl acrylate is used as the base resin.

[0052] Comparative Example 3 refers to the parameter conditions in Example 1, except that ethyl 2,4,6-trimethylbenzoylphenylphosphonate is used as the photoinitiator.

[0053] Comparative Example 4 refers to the parameter conditions in Example 1, except that no modified photoinitiator is added.

[0054] Comparative Example 5 refers to the parameter conditions in Example 1, except that the stirring time is 5 h.

[0055] Comparative Example 6 refers to the parameter conditions in Example 1, except that the stirring time is 0.2 h.

[0056] Comparative Example 7 refers to the parameter conditions in Example 1, except that ethyl acetate was added to S1 as a volatile solvent to participate in the reaction.

[0057] Experimental Example 1 Adhesion Test

[0058] Adhesion tests were performed on Examples 1-6 and Comparative Examples 1-7 according to the international standard ISO 2409. The rating scale was 0-5, where 0 indicated that no coating or photoresist had fallen off in the grid area, indicating the best adhesion; and 5 indicated that the coating or photoresist had fallen off in more than 65% of the grid area, indicating the worst adhesion. The results are shown in Table 1.

[0059] Table 1 Parameters and adhesion test of Examples 1-6 and Comparative Examples 1-7

[0060]

[0061]

[0062] It can be seen from Table 1 that in Comparative Examples 1-2, when only pentaerythritol triacrylate or isobornyl acrylate is used as the matrix resin, the adhesion is lower than that of Examples 1-6. This is because the excessively high cross-linking density of pentaerythritol triacrylate may cause the photoresist to generate greater internal stress during the curing process. When the internal stress exceeds the adhesion between the photoresist and the substrate, the photoresist will be peeled off from the substrate, reducing the adhesion. Since isobornyl acrylate has fewer functional groups and a relatively low cross-linking density, the cohesive force of the photoresist may be weak. When subjected to a large external force, the photoresist is easily deformed or damaged, thereby reducing the adhesion between it and the substrate. When the two are compounded, the carboxyl groups in the composite resin can undergo an esterification reaction with the silanol groups in the matrix material to form a stable ester bond, thereby firmly connecting the photoresist to the substrate and significantly enhancing the adhesion between the photoresist and the substrate. In Comparative Examples 3-4, when only 2,4,6-trimethylbenzoylphenylphosphonate was used as a photoinitiator or no modified photoinitiator was used, the adhesion of the photoresist was significantly worse than that of the examples. By introducing amino groups into 2,4,6-trimethylbenzoylphenylphosphonate, the amino groups can react chemically with the groups of the substrate to form hydrogen bonds during the photoresist curing process, thereby enhancing the adhesion of the photoresist to the substrate. The introduction of amino groups also gives the modified photoinitiator higher photoinitiator activity. Under light conditions, the modified photoinitiator can more quickly and efficiently generate active species such as free radicals or cations, which react with the resin components to form a more compact and stable network structure, thereby enhancing the internal cohesion of the photoresist and the interaction between the photoresist and the substrate. In Comparative Examples 5-6, the control of the stirring time also has a certain impact on the adhesion of the photoresist. A stirring time that is too long or too short will affect the internal cross-linking process, thereby affecting the adhesion. There is also a certain degree of synergy between the composite resin and the modified photoinitiator. The free radicals generated by the modified photoinitiator can trigger polymerization reactions between acrylate groups. At the same time, they can also cross-link the composite resin with other additives containing polymerizable groups, forming a three-dimensional network structure, thereby enhancing the overall cohesion of the photoresist and its adhesion to the substrate, thereby improving the stability of the photoresist. In Comparative Example 7, a volatile solvent was used, but its effect was less than that of the embodiment. This volatile solvent is highly toxic and flammable, which actually reduces the stability of the photoresist.

[0063] Examples 7-12 refer to the parameter conditions in Example 4, except that the amounts of the composite cross-linking agent and the modified curing agent are controlled and the parameters thereof are changed, as shown in Table 2.

[0064] Comparative Example 8 refers to the parameter conditions in Example 4, except that only γ-methacryloxypropyltrimethoxysilane is used as the crosslinking agent.

[0065] Comparative Example 9 refers to the parameter conditions in Example 4, except that only hexamethoxymethylmelamine is used as the cross-linking agent.

[0066] Comparative Example 10 refers to the parameter conditions in Example 4, except that no composite cross-linking agent is added.

[0067] Comparative Example 11 refers to the parameter conditions in Example 4, except that only benzoin dimethyl ether is used as the curing agent.

[0068] Comparative Example 12 refers to the parameter conditions in Example 4, except that no modified curing agent is used.

[0069] Experimental Example 2 Tensile Strength and Shrinkage Test

[0070] The tensile strength of Example 4, Examples 7-12, and Comparative Examples 8-12 was tested using a single-column servo-controlled computer system tensile testing machine. A metal mold with a size of 10*10*1mm and a polytetrafluoroethylene coating was filled with photoresist and UV-cured. The shrinkage rate of the four sides of the molded glue was tested, which is the shrinkage rate of the photoresist. The results are shown in Table 2.

[0071] Table 2 Parameters, tensile strength and shrinkage test of Example 4, Examples 7-12 and Comparative Examples 8-12 It can be found from Table 2 that in Comparative Examples 8-10, the tensile strength of the photoresist is significantly lower than that of Examples 4 and Examples 7-12, and the shrinkage rate is significantly higher than that of Examples 4 and Examples 7-12. Mixing γ-methacryloxypropyltrimethoxysilane and hexamethoxymethylmelamine in proportion to form a composite cross-linking agent can make the cross-linking reaction of certain components in the photoresist more sufficient and efficient, so that the structure of the cross-linked network can be further optimized, thereby improving the tensile strength of the photoresist. γ-methacryloxypropyltrimethoxysilane has a certain flexible cross-linking structure. This flexible structure can absorb and buffer the shrinkage stress generated by the cross-linking reaction during the curing process of the photoresist, thereby reducing the degree of shrinkage. In Comparative Examples 11-12, only benzoin dimethyl ether is used as a curing agent or no modified curing agent is used, and the stability of the photoresist is significantly lower than that of the embodiment. This is because the modified curing agent is a compound of benzoin dimethyl ether and β-cyclodextrin, which can chemically react with the composite resin to form a more stable, uniform and dense three-dimensional cross-linked network, thereby improving the tensile strength of the photoresist; and the modified curing agent can control the curing reaction speed of the photoresist by adjusting its molecular structure and reaction activity. The slower curing speed can allow the photoresist to have more time for molecular rearrangement during the curing process, reduce the internal stress generated by rapid molecular cross-linking, and thus improve the stability of the photoresist. The modified curing agent and the composite cross-linking agent cooperate with each other during the photoresist curing process to jointly build a more complete cross-linking network. The modified curing agent can provide a suitable environment and conditions for the reaction of the composite cross-linking agent, while the composite cross-linking agent can further enhance and expand the cross-linking network formed by the modified curing agent, showing higher tensile strength; in terms of reducing shrinkage, the modified curing agent reduces shrinkage by controlling the reaction rate and compensating for shrinkage, while the composite cross-linking agent reduces shrinkage by forming a flexible structure and dispersing stress, thereby improving the stability of the photoresist.

[0072] Examples 13-18 refer to the parameter conditions in Example 9, except that the amounts of fluorinated silicone nanoparticles and polyimide microspheres and the parameter changes therein are controlled, as shown in Table 3.

[0073] Table 3 Parameter conditions of Example 9 and Examples 13-18

[0074]

[0075] Comparative Example 13 refers to the parameter conditions in Example 9, except that only heptadecafluorodecyltrimethoxysilane is used and nanoparticles are not prepared.

[0076] Comparative Example 14 refers to the parameter conditions in Example 9, except that no fluorinated silicone nanoparticles are added.

[0077] Comparative Example 15 refers to the parameter conditions in Example 9, except that only pyromellitic dianhydride is used and polyimide microspheres are not prepared.

[0078] Comparative Example 16 refers to the parameter conditions in Example 9, except that no polyimide microspheres are added.

[0079] Experimental Example 3 Acid and alkali resistance and adhesion test

[0080] Acid etching resistance was tested by drying the developed substrate, immersing it in 3% hydrochloric acid, etching it for 30 minutes, then rinsing it with water, drying it, and observing any changes in the film surface. Alkali etching resistance was tested by drying the developed substrate, immersing it in a 30% sodium hydroxide solution, etching it for 30 minutes, then rinsing it with water, drying it, and observing any changes in the film surface. Adhesion was tested according to the test method in Experimental Example 1. The results are shown in Table 4.

[0081] Table 4 Acid and alkali resistance and adhesion test of Example 9, Examples 13-18 and Comparative Examples 13-16

[0082] Example Acid etching resistance Alkali etching resistance Adhesion / Grade Example 9 No change after 72 hours No change after 72 hours 1 Example 13 No change after 72 hours No change after 72 hours 1 Example 14 No change after 96 hours No change after 96 hours 1 Example 15 No change after 96 hours No change after 96 hours 0 Example 16 No change after 96 hours No change after 72 hours 0 Example 17 No change after 72 hours No change after 72 hours 1 Example 18 No change after 72 hours No change after 72 hours 1 Comparative Example 13 Fall off after 72 hours Fall off after 72 hours 2 Comparative Example 14 Fall off after 48 hours Fall off after 48 hours 3 Comparative Example 15 Fall off after 72 hours Fall off after 72 hours 2 Comparative Example 16 Fall off after 48 hours Fall off after 48 hours 3

[0083] It can be found from Table 4 that in Comparative Examples 13-14, the acid and alkali resistance of the photoresist is significantly worse than that of Examples 9 and 13-18, and the adhesion is also lower than that of the examples, indicating that the fluorine-containing silicone nanoparticles play an important role in the photoresist. Because the fluorine atoms in the fluorine-containing silicone nanoparticles have extremely high electronegativity, the C-F bonds formed have high bond energy and good chemical stability. This property makes the nanoparticles themselves highly tolerant to acids and alkalis. When they are uniformly dispersed in the photoresist, they can form a chemically stable barrier inside the photoresist, preventing acid or alkali molecules from penetrating into the photoresist, thereby protecting the photoresist from acid and alkali corrosion; and the fluorine-containing silicone nanoparticles have a large specific surface area and high surface activity. During the photoresist coating process, these nanoparticles can chemically react with atoms or groups on the substrate surface, making the connection between the photoresist and the substrate tighter, thereby improving the adhesion of the photoresist and the stability. In Comparative Examples 15-16, the acid and alkali resistance and adhesion of the photoresist are also significantly lower than those of the examples. This is because the polyimide microspheres form a physical barrier network within the photoresist. The microspheres block the diffusion of acid or alkali molecules, increasing the diffusion path and difficulty within the photoresist, reducing the rate and extent of acid and alkali erosion, and thus protecting the photoresist. Furthermore, the polyimide microspheres have a certain rigid structure. During the photoresist curing process, the microspheres partially embed into the microscopic pores or roughness structure of the substrate surface, forming a mechanical interlocking effect that firmly fixes the photoresist to the substrate and significantly improves the adhesion between the photoresist and the substrate. The fluorosilicone nanoparticles and polyimide microspheres interact within the photoresist to form a composite protective structure. Nanoparticles provide a chemically stable barrier at the microscopic level, while microspheres form a physical barrier network at the macroscopic level. This composite structure can resist acid and alkali erosion from different scales and angles, further improving the acid and alkali resistance of the photoresist. The two also have a synergistic effect in enhancing adhesion. Nanoparticles are tightly combined with the substrate through surface activity and improved interface properties, and microspheres fix the photoresist on the substrate through mechanical intercalation and improved stress distribution. Their joint action makes the connection between the photoresist and the substrate stronger, and the adhesion is significantly improved, thereby improving the stability of the photoresist.

[0084] Examples 19-24 refer to the parameter conditions in Example 15, except that the amount of the composite dispersant is controlled and the parameter conditions for preparing the photoresist are specifically shown in Table 5.

[0085] Comparative Example 17 refers to the parameter conditions in Example 15, except that only fatty alcohol polyoxyethylene ether is used as the dispersant.

[0086] Comparative Example 18 refers to the parameter conditions in Example 15, except that only sodium dodecylbenzenesulfonate is used as the dispersant.

[0087] Comparative Example 19 refers to the parameter conditions in Example 15, except that no composite dispersant is added.

[0088] Comparative Example 20 refers to the parameter conditions in Example 15, except that the ultrasonic treatment time in S2 is 2 hours and the stirring time is 8 hours; the stirring time in S3 is 4 hours.

[0089] Comparative Example 21 refers to the parameter conditions in Example 15, except that the ultrasonic treatment time in S2 is 5 minutes and the stirring time is 0.5 hours; the stirring time in S3 is 10 minutes.

[0090] Experimental Example 4 Uniformity Test

[0091] The photoresist was spin-coated on a 6-inch silicon wafer at 1200 rpm for 90 seconds, and then baked at 120° C. for 5 minutes. The film thickness at 20 points was tested. The uniformity was calculated as follows: (maximum film thickness - minimum film thickness) / 2 times the average film thickness × 100%. The results are shown in Table 5. The uniformity of the photoresist of Example 21 and Comparative Examples 17-21 is shown in Table 5. Figure 1 shown.

[0092] Table 5 Parameter conditions and uniformity test of Example 15, Examples 19-24 and Comparative Examples 17-21

[0093]

[0094]

[0095] From Table 5 and Figure 1It can be found that in Comparative Examples 17-19, the use of a single dispersant or the absence of a composite dispersant will have an adverse effect on the uniformity of the photoresist, resulting in reduced stability of the photoresist. The addition of a composite dispersant in the embodiment has better overall uniformity. The composite dispersant can reduce the surface tension between the components in the photoresist, so that the components can be evenly dispersed in the system. In the photoresist, the composite dispersant molecules will be adsorbed on the surface of the solid particles to form a protective film, so that the particles maintain a certain distance from each other and maintain a dispersed state. In Comparative Examples 20-21, if the ultrasonic and stirring time is too long or too short, the uniformity of the photoresist will be affected. If the ultrasonic stirring time is too long, the components in the photoresist may be damaged. The high-intensity ultrasonic action may cause the degradation of the high-molecular polymer, change the chemical structure and properties of the photoresist, and may also cause the temperature of the photoresist system to be too high, causing the photoinitiator to decompose prematurely, and reducing the stability of the photoresist; if the ultrasonic stirring time is too short, the particle agglomerates are difficult to be completely broken up, and the components cannot be fully mixed, which will result in the presence of larger-sized particle clusters and areas with uneven distribution of components in the photoresist, affecting the uniformity of the photoresist. During photolithography, these uneven areas will lead to inconsistent exposure and development effects, and the formed pattern will have defects, such as uneven line thickness, holes, etc. In the embodiment, controlling the time of ultrasound and stirring can make the photoresist have good uniformity. The power of ultrasound can break the agglomeration structure between various particles in the photoresist and disperse large particles into small particles, which is beneficial to improving the uniformity of the photoresist. The shear force generated during the stirring process can also disperse larger particle agglomerates to a certain extent, assisting the ultrasonic dispersion effect, thereby improving the stability of the photoresist.

[0096] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a volatile solvent-free photoresist, characterized in that: The preparation method comprises the following steps in parts by weight: S1: adding 40-60 parts of a composite resin into a reaction vessel, slowly adding 5-9 parts of a modified photoinitiator at a rotation speed of 500 rpm, and continuously stirring for 1 hour to 2 hours to form a uniform mixed solution; the composite resin includes pentaerythritol triacrylate and isobornyl acrylate; S2: 1-3 parts of a composite crosslinking agent, 0.5-0.9 parts of a modified curing agent, 0.1-0.5 parts of fluorinated silicone nanoparticles, 0.1-0.3 parts of polyimide microspheres, and 0.2-0.4 parts of a composite dispersant are added one by one to the mixed solution at a rotation speed of 500 rpm, ultrasonicated at 20 kHz for 10 min-30 min in an ultrasonic machine, and then stirred at 800 rpm for 2 h-4 h to obtain a photoresist precursor solution; S3: degassing the photoresist precursor solution, evacuating the reaction container to a vacuum state, and slowly stirring at a rotation speed of 50 rpm for 20 min to 60 min to eliminate bubbles, and obtaining the photoresist after the treatment; The modified photoinitiator is prepared by adding 8-12 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 10 parts of toluene into a reactor, stirring for 30 minutes, then adding 1 part of ethylenediamine and 0.2 parts of triethylamine, heating the reaction system to 80° C., and stirring for 8 hours under the heating condition. After the reaction is completed, the reaction solution is cooled to room temperature, the organic solvent is removed by distillation, and then dried in a vacuum drying oven at 60° C. for 12 hours to obtain the modified photoinitiator; The composite cross-linking agent is a mixture of γ-methacryloxypropyltrimethoxysilane and hexamethoxymethyl melamine; The modified curing agent is formed by compounding benzoin dimethyl ether and β-cyclodextrin; The composite dispersant is prepared by mixing fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate.

2. The method for preparing a volatile solvent-free photoresist according to claim 1, wherein: The composite resin is prepared by adding 19-24 parts of pentaerythritol triacrylate into a three-necked flask, then slowly adding 8 parts of isobornyl acrylate, while turning on a stirrer and setting the stirring speed to 300 rpm; placing the three-necked flask in a constant temperature water bath, controlling the temperature at 60°C, and continuously stirring for 90 minutes to obtain a mixture; and slowly adding 0.1 parts of p-hydroxyanisole to the mixture while stirring, and continuously stirring for 60 minutes to obtain the composite resin.

3. The method for preparing a volatile solvent-free photoresist according to claim 1, wherein: The weight ratio of the γ-methacryloxypropyltrimethoxysilane to the hexamethoxymethylmelamine is 1-5:

1.

4. The method for preparing a volatile solvent-free photoresist according to claim 1, wherein: The modified curing agent is prepared by placing 3-7 parts of benzoin dimethyl ether and 20 parts of anhydrous ethanol in a flask, stirring at room temperature for 30 minutes to form a transparent solution; placing 2 parts of β-cyclodextrin and 20 parts of deionized water in another flask, stirring at 60° C. for 40 minutes to form a clear solution; Under continuous stirring and 60° C., the transparent solution was slowly added dropwise to the clear solution, with the dropping speed controlled at 2 drops per second. After the dropwise addition was completed, the reaction was continued with stirring at 60° C. for 2 h to 6 h to obtain a reaction solution; the reaction solution was naturally cooled to room temperature, and then refrigerated and allowed to stand at 4° C. for 12 h; after the standing period, the reaction solution was centrifuged at 4000 rpm for 15 min to separate the precipitate, and the precipitate was washed 5 times with deionized water. Then, the precipitate was placed in a vacuum drying oven and dried at 50° C. for 24 h to obtain the modified curing agent.

5. The method for preparing a volatile solvent-free photoresist according to claim 1, wherein: The preparation method of the fluorinated silicone nanoparticles comprises: mixing 1 part of heptafluorodecyltrimethoxysilane and 1-5 parts of ethyl orthosilicate, then adding 10 parts of ethanol, and stirring for 60 minutes to obtain a mixed solution A; slowly dropwise adding 1 part of a 0.1 mol / L ammonia solution into the mixed solution A, and continuously stirring for 2 hours to 4 hours. After the reaction is completed, the mixed solution A is allowed to stand for 2 hours, and then the precipitate is washed out by centrifugation, and the precipitate is vacuum dried at 60° C. for 12 hours to obtain the fluorinated silicone nanoparticles.

6. The method for preparing a volatile solvent-free photoresist according to claim 1, wherein: The preparation method of the polyimide microspheres comprises the following steps: dissolving 1 to 3 parts of pyromellitic dianhydride in 5 parts of N,N-dimethylformamide to obtain solution A; dissolving 3 parts of 4,4'-diaminodiphenyl ether in 5 parts of N,N-dimethylformamide to obtain solution B; slowly adding solution A dropwise to solution B to form a prepolymer solution; then adding 0.2 parts of sodium lauryl sulfate to the prepolymer solution, and continuously stirring for 30 minutes to form a stable emulsion; adding 0.1 parts of potassium persulfate to the emulsion, stirring for 1 hour, and reacting at 100°C for 4 to 8 hours. After the reaction is completed, centrifuging and washing the precipitate, and finally drying it in a vacuum drying oven at 60°C for 12 hours to obtain the polyimide microspheres.

7. The method for preparing a volatile solvent-free photoresist according to claim 1, wherein: The weight ratio of the fatty alcohol polyoxyethylene ether to the sodium dodecylbenzenesulfonate is 1-3:

2.

8. A volatile solvent-free photoresist, characterized in that: The photoresist is prepared by the preparation method according to any one of claims 1 to 7; the synthetic raw materials of the photoresist include composite resin, modified photoinitiator, composite crosslinking agent, modified curing agent, fluorinated silicone nanoparticles, polyimide microspheres and composite dispersant.

Images