An alkali-soluble photoresist resistant to HF resist removal and its preparation method

Abstract

This invention relates to the field of photolithography, specifically to a photoresist resistant to HF and alkali-soluble during resist removal, and its preparation method. This invention overcomes the problems of poor hydrofluoric acid resistance and poor alkali solubility in existing photoresists. A modified phenolic resin is obtained by introducing silicon-oxygen bonds, and a modified acrylate is obtained by adding a fluorinated acrylate monomer. The modified phenolic resin, modified acrylate, propylene glycol methyl ether acetate, photosensitive material, and additives are stirred, dispersed, filtered, and impurities removed to obtain a photoresist colloid. The photoresist colloid is then stirred and dispersed with modified nano-titanium dioxide, and impurities are removed to obtain a hydrofluoric acid-resistant, alkali-soluble photoresist. By introducing rigid silicon-oxygen groups and rigid fluorine-containing groups, and synergistically using modified nano-titanium dioxide to fill the voids in the photoresist resin, the hydrofluoric acid resistance of the photoresist is improved. Simultaneously, after acid etching, the resin voids are utilized to increase the alkali solubility rate, reducing contaminant generation and the use of organic solvents during resist removal.

Description

Technical Field

[0001] This invention relates to the field of photolithography, specifically to an alkali-soluble photoresist resistant to HF resist removal and its preparation method. Background Technology

[0002] Photoresist, also known as photoresist, is a light-sensitive liquid mixture composed of three main components: photosensitive resin, photosensitive agent, and solvent. It can undergo cross-linking curing or degradation reactions under light irradiation. Photoresist is photochemically sensitive and uses photochemical reactions to transfer the required micro-patterns from the template (mask) to the substrate to be processed through processes such as exposure and development. Then, it is processed by etching, diffusion, ion implantation, and other processes.

[0003] Photoresist is a key material used in semiconductor manufacturing to create patterned chips. It undergoes a chemical reaction in the exposed areas, causing a significant difference in solubility between exposed and unexposed areas in an alkaline solution. After treatment with an appropriate solvent, the soluble portion is dissolved, yielding the desired image. Based on different imaging mechanisms, photoresists can be classified into negative and positive photoresists. Positive photoresists, under illumination of a certain wavelength of light, undergo a decomposition reaction in the illuminated areas, increasing their solubility and creating a greater difference in solubility between exposed and unexposed areas. Using a suitable developer, the exposed soluble portion can be removed, ultimately forming an image on the processed surface that matches the mask.

[0004] Currently, photoresist systems are classified into phenolic, cyclic rubber, acrylic, and polyimide systems. Among existing technologies, only cyclic rubber photoresists can meet the etching requirements of hydrofluoric acid etching liquid. However, common negative photoresists in cyclic rubber systems are not water-soluble and require organic developing solutions, which, along with organic rinsing solutions, cause significant environmental pollution.

[0005] In chain lithography machines used in photovoltaic applications, photoresist that can withstand high concentrations of hydrofluoric acid is a major type. If it cannot withstand a certain concentration of hydrofluoric acid solution during the etching process, it will cause the photoresist to fall off, thus affecting the imaging process. In addition, if the cured adhesive in the photoresist removal stage is insoluble and adheres to the rollers of the chain machine, it will contaminate the back of the silicon wafer, making subsequent cleaning difficult and generating solid waste, which in turn pollutes the environment.

[0006] To address this, an alkali-soluble photoresist resistant to HF resist removal and its preparation method are proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a photoresist resistant to hydrofluoric acid and alkali-soluble by resisting photoresist removal, and its preparation method. A modified phenolic resin is obtained by introducing silicon-oxygen bonds, and a modified acrylate is obtained by adding a fluorinated acrylate monomer. The modified phenolic resin, modified acrylate, propylene glycol methyl ether acetate, photosensitive material, and additives are stirred, dispersed, filtered, and impurities removed to obtain a photoresist colloid. The photoresist colloid is then stirred and dispersed with modified nano-titanium dioxide, and impurities are removed to obtain a photoresist resistant to hydrofluoric acid and alkali-soluble by resisting photoresist removal. By introducing rigid silicon-oxygen groups and rigid fluorinated groups, and utilizing the stacking ability between the rigid conjugated benzene rings, a tight stack can be formed, increasing the resistance to hydrofluoric acid. By adding modified nano-titanium dioxide, the photoresist resin structure cannot maintain sufficient filling of voids after acid etching, allowing moisture and alkali molecules to penetrate the resin structure through the voids, increasing the alkali dissolution rate and improving the resist-removal alkali-soluble performance of the photoresist after acid etching.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] This invention provides an alkali-soluble photoresist that resists HF resist removal, wherein the photoresist comprises a photoresist colloid and modified nano-titanium dioxide;

[0010] The photoresist colloid comprises 45-75 parts of modified phenolic resin, 12-25 parts of modified acrylate, 5-15 parts of photosensitizer, 160-240 parts of solvent and emulsion additives.

[0011] The modified phenolic resin is prepared by using phenolic compounds, aldehyde compounds, and modifier one; the modified acrylate is prepared by using styrene acrylate, acrylic acid, and modifier two.

[0012] The mass ratio of the photoresist colloid to the modified nano-titanium dioxide is 8-12:1;

[0013] The emulsion additives include silicone oil and antioxidant 1010.

[0014] Preferably, the viscosity of the photoresist is 500-800 mPa·s; the molecular weight of the modified phenolic resin is 5000-10000; the molecular weight of the modified acrylate is 1000-2000; and the coating thickness of the photoresist is 10-25 μm.

[0015] Preferably, the phenolic compound is selected from one of α-naphthol, nonylphenol, phenol, and phenylphenol; the aldehyde compound is selected from one of salicylaldehyde, formaldehyde, and furfural; and the molar ratio of the phenolic compound to the aldehyde compound is 1:1.2-1.8.

[0016] Preferably, the mass ratio of the modified phenolic resin to the modified acrylate is 1-5:1; the solvent is propylene glycol methyl ether acetate.

[0017] Preferably, the first modifier is selected from one of hydroxyl-terminated polydiphenylsiloxane, hydroxyl-terminated polyphenylmethylsiloxane, and hydroxyl-terminated polydimethylsiloxane; the second modifier is selected from one of hexafluorophenylpropyl methacrylate, perfluorooctyl ethyl acrylate, and methacrylic acid.

[0018] Preferably, the photosensitizer is a mixture of 2-hydroxy-2-methyl-1-phenylpropanone and sodium diazonoquinone sulfonate; the mass ratio of 2-hydroxy-2-methyl-1-phenylpropanone to sodium diazonoquinone sulfonate is 1-5:1.

[0019] The present invention also provides a method for preparing the alkali-soluble photoresist that is resistant to HF resist removal as described above, wherein the preparation of the photoresist includes the following steps:

[0020] Modified phenolic resin was added to a three-necked flask, followed by propylene glycol methyl ether acetate. The resin was dissolved completely under nitrogen protection and stirring at 30°C to obtain a homogeneous solution. Modified acrylate was slowly added to the homogeneous solution, and the mixture was stirred at 300 rpm for 30 minutes to obtain a mixed solution. A photosensitive substance was slowly added to the propylene glycol methyl ether acetate, and the mixture was continuously stirred until homogeneous to obtain a dispersion. The dispersion was slowly added to the mixed solution, and the mixture was stirred until homogeneous. Silicone oil and stabilizer 1010 were then added, and the mixture was heated to 40°C and stirred for 2 hours. The mixture was filtered through a filter membrane to remove impurities, yielding a photoresist colloid.

[0021] KH-792 was dissolved in 95% ethanol solution, and the pH of the system was adjusted to 3 with acetic acid. The mixture was stirred in a magnetic stirrer at 50°C for 2 hours to obtain a silane coupling agent solution. Nano-titanium dioxide was slowly added to the silane coupling agent solution, and the reaction was carried out for 2 hours to obtain a modified system. The modified system was dried and ground to obtain modified nano-titanium dioxide. The modified nano-titanium dioxide was added to the photoresist colloid, and the mixture was stirred at 200-400 rpm for 1-3 hours at 30-60°C. The mixture was then filtered through a filter membrane to remove impurities, and the photoresist was obtained.

[0022] Preferably, the preparation of the modified phenolic resin includes the following steps:

[0023] A phenolic compound, an aldehyde compound, and a modifier were dried in a vacuum drying oven at 80°C for 2 hours to obtain a dried material. 20 parts of the phenolic compound, aldehyde compound, and modifier were sequentially added to a three-necked flask and heated to 50°C to mix thoroughly, thus obtaining a mixed system. 30 parts of a 30% sodium hydroxide solution were added to the mixed system and stirred for 10 minutes to obtain a reaction system. The reaction system was heated to 70°C and kept at this temperature for 5 hours to obtain a reaction product. Citric acid solution was added to the reaction product to adjust the pH to neutral, and the mixture was left overnight. After centrifugation, filtration, and washing, the modified phenolic resin was obtained. The modifier accounted for 20% of the total phenolic resin mass.

[0024] Preferably, the preparation of the modified acrylate includes the following steps:

[0025] Azobisisobutyronitrile (AIBN) was added to deionized water and stirred at 300 rpm to obtain an emulsion. The emulsion was then added to a flask, and potassium persulfate was added at 100 rpm. Styrene acrylate, acrylic acid, and hexafluorophenyl propyl methacrylate were stirred to prepare a pre-emulsion. Potassium persulfate was added to the pre-emulsion, and the mixture was stirred at 200 rpm for 20 minutes under nitrogen protection to obtain a mixed system. The mixed system was heated to 80°C, and after blue light appeared, potassium persulfate was added again, and the mixture was kept at this temperature for 10 minutes to obtain a reaction system. The reaction system was heated to 90°C and kept at this temperature for 3 hours to obtain a reactant. The reactant was cooled to 40°C to obtain a reaction product. Ammonia was added to the reaction product to adjust the pH to 7-8, and the gel was filtered through gauze to obtain the modified acrylate. The mass ratio of styrene acrylate, acrylic acid, and modifier II was 12:5:3.

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

[0027] 1. This invention controls the modified phenolic resin obtained by reacting a type of modifier with sodium hydroxide solution to use as the base resin of the photoresist by adjusting the types and amounts of phenolic and aldehyde compounds. Modified acrylic resin obtained by two-step initiation polymerization of acrylic monomer and modifier is used as the crosslinking monomer. The conjugated structure of benzene ring and the polar effect of hydroxyl group enhance the intermolecular forces, form a stable crosslinking structure, and improve the heat resistance of the photoresist.

[0028] 2. This invention adjusts the types of modifier one and modifier two, and utilizes the introduction of benzene-containing siloxane and fluorinated phenyl acrylate. By taking advantage of the stacking ability between the rigid conjugated systems of benzene rings, a tight stack can be formed. This, combined with the effect of nano-titanium dioxide filling the resin gaps, slows down or prevents the intrusion of hydrofluoric acid solution from the interface edge and above the adhesive-substrate bond, thus achieving good hydrofluoric acid resistance. At the same time, the high hydrophobicity and high reactivity of the silicon-oxygen bond and the low surface energy of the fluorine atom can effectively resist the corrosive effect of hydrofluoric acid on the photoresist.

[0029] 3. This invention controls the preparation method of modified acrylate, changes the type of acrylic monomer, adjusts the viscosity of photoresist by modifying acrylate, and controls the type of solvent to synergistically improve the adhesion between photoresist and substrate by sodium diazonoquinone sulfonate, which helps to maintain the integrity of photoresist pattern and make the generated pattern have good resolution.

[0030] 4. This invention introduces modified nano-titanium dioxide into the photoresist colloid. By stirring and mixing, and controlling the stirring parameters, the uniformity of the mixing between the modified nano-titanium dioxide and the colloid is adjusted, ensuring that the nano-titanium dioxide fully fills the resin voids. After the hydrofluoric acid etching process, the nano-titanium dioxide reacting on the surface cannot maintain sufficient filling of the voids in the photoresist resin structure. Moisture and alkali molecules penetrate through the voids into the interior of the resin structure, promoting the breaking of chemical bonds in the resin structure, increasing the alkali dissolution rate of photoresist removal, and reducing the generation of contaminants and organic solvents during the photoresist removal process. Attached Figure Description

[0031] Figure 1 The graph shows the change in mass retention rate as a function of temperature for Embodiment 1 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0034] The KH-792 of this invention is N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, CAS: 1760-24-3; the KH-570 is methacryloyloxypropyltrimethoxysilane, CAS: 2530-85-0.

[0035] Please see Figure 1 This invention provides an alkali-soluble photoresist resistant to HF resist removal and its preparation method, the technical solution of which is as follows:

[0036] Example 1

[0037] α-Naphthol, salicylaldehyde, and hydroxyl-terminated polydiphenylsiloxane were dried in a vacuum drying oven at 80°C for 2 hours to obtain a dried material. The phenylphenol, salicylaldehyde, and hydroxyl-terminated polydimethylsiloxane were sequentially added to a three-necked flask and heated to 50°C to mix thoroughly, thus obtaining a mixed system. 30 parts of a 30% sodium hydroxide solution were added to the mixed system, and the mixture was stirred for 10 minutes to obtain a reaction system. The reaction system was heated to 70°C and maintained at this temperature for 5 hours to obtain a reaction product. Citric acid solution was added to the reaction product to adjust the pH to neutral, and the mixture was left to stand overnight. After centrifugation, filtration, and washing, modified phenolic resin was obtained. The hydroxyl-terminated polydimethylsiloxane accounted for 20% of the total mass of the phenolic resin.

[0038] Five parts of azobisisobutyronitrile (AIBN) were added to 20 ml of deionized water and stirred at 300 rpm to obtain an emulsion. The emulsion was then added to a flask, and 0.5 parts of potassium persulfate were added at 100 rpm. 60 parts of styrene acrylate, 25 parts of acrylic acid, and 15 parts of hexafluorophenyl propyl methacrylate were stirred for 30 min to obtain a pre-emulsion. 0.5 parts of potassium persulfate were added to the pre-emulsion, and the mixture was stirred at 200 rpm for 20 min under nitrogen protection to obtain a mixed system. The mixed system was heated to 80°C and reacted. After blue light appeared, 0.5 parts of potassium persulfate were added, and the mixture was kept at this temperature for 10 min to obtain a reaction system. The reaction system was heated to 90°C and kept at this temperature for 3 h to obtain a reactant. The reactant was cooled to 40°C to obtain a reaction product. The reaction product was adjusted to pH 7-8 with ammonia water, and the gel was filtered through gauze to obtain modified acrylate.

[0039] 60 parts of modified phenolic resin were added to a clean, dry three-necked flask, and 200 parts of propylene glycol methyl ether acetate were added. The resin was fully dissolved under nitrogen protection and stirring at 30°C to obtain a homogeneous solution. 20 parts of modified acrylate were slowly added to the homogeneous solution and stirred at 300 rpm for 30 min to obtain a mixture. 10 parts of photosensitive material (including 2.5 parts of 2-hydroxy-2-methyl-1-phenylpropanone and 7.5 parts of 1,4-diazonaphthoquinone) were slowly added to the propylene glycol methyl ether acetate and stirred continuously until uniformly dispersed to obtain a dispersion. The dispersion was slowly added to the mixture and stirred at 200 rpm until uniform. Then, 5 parts of silicone oil and 10103 parts of stabilizer were added, and the mixture was heated to 40°C and stirred for 2 h. The mixture was filtered through a 0.2 μm pore size filter membrane to remove impurity particles to obtain a photoresist colloid.

[0040] Five parts of KH-792 were dissolved in 95% ethanol solution, and the pH of the system was adjusted to 3 with acetic acid. The solution was stirred in a magnetic stirrer at 50°C for 2 hours to obtain a silane coupling agent solution. Thirty parts of nano-titanium dioxide were slowly added to the silane coupling agent solution and reacted at 50°C for 2 hours to obtain a modified system. The modified system was dried at 80°C for 2 hours and ground for 30 minutes to obtain modified nano-titanium dioxide. Ten parts of the modified nano-titanium dioxide were added to 100 parts of the photoresist colloid and stirred at 300 rpm for 1 hour at 30°C. Impurity particles were removed by filtration through a 0.2 μm pore size filter membrane to obtain an alkali-soluble photoresist that is resistant to HF and can be removed by resisting photoresist removal.

[0041] Examples 2-10 follow the same preparation method and parameter conditions as Example 1, with differences shown in Table 1.

[0042] Table 1. Component variations in Examples 1-10

[0043]

[0044] Comparative Example 1 follows the same preparation method and parameters as Example 1, except that no terminal hydroxyl polydiphenylsiloxane is added.

[0045] Comparative Example 2 follows the same preparation method and parameters as Example 1, except that hexafluorophenyl methacrylate is not added.

[0046] Comparative Example 3 was prepared using the same method and parameters as in Example 1, but without the addition of terminal hydroxyl polydiphenylsiloxane and hexafluorophenyl methacrylate.

[0047] Example 11 Heat Resistance Test

[0048] The HF-resistant, alkali-soluble photoresists prepared in Examples 1-10 and Comparative Examples 1-2 were added to a hot-press mold and cured at 80°C for 40 min to obtain a photoresist film. The thermal stability of the film was tested using a TGA / Q50 thermogravimetric analyzer (purchased from Mettler Toledo Technologies). A 5 mg sample was taken under nitrogen protection at a flow rate of 50 mL / min. The test temperature ranged from 25 to 500°C, with a heating rate of 10°C / min. The T0 values ​​were measured. 5％( (temperature at 5% weight loss) and T 80％( The temperature at which the weight loss rate was 80% was determined, and the results are shown in Table 1. Figure 1 The graph shows the change in mass retention rate as a function of temperature for Example 1 and Comparative Examples 1-3.

[0049] Table 1. Heat resistance performance determination of Examples 1-10 and Comparative Examples 1-2

[0050] Example <![CDATA[T5℃]]> <![CDATA[T 80 ℃]]> Example 1 188 322 Example 2 162 295 Example 3 174 308 Example 4 183 312 Example 5 155 282 Example 6 185 316 Example 7 187 318 Example 8 188 325 Example 9 164 302 Example 10 192 328 Comparative Example 1 128 268 Comparative Example 2 132 272 Comparative Example 3 103 252

[0051] pass Figure 1The results show that the weight loss of the prepared photoresist film mainly occurs in three stages. The first stage is from 50 to 200°C. During this stage, the material contains a small amount of H2O and unreacted hydroxymethyl and ether bonds, which gradually react to generate methylene groups and cause weight loss due to the volatilization of H2O during the heating process. The second stage is from 200 to 400°C, which is the main stage of weight loss of the photoresist film. This is because the modified phenolic resin and modified acrylate decompose at high temperatures to generate small molecules. The third stage is after 400°C when the mass tends to stabilize, at which point only inorganic components exist in the system. As shown in Table 1, the heat resistance of the photoresist prepared in Comparative Example 3 without the addition of hydroxyl polydiphenylsiloxane and hexafluorophenyl propyl methacrylate is significantly reduced compared to the examples. The introduction of siloxane bonds and fluorinated groups significantly improves the heat resistance of the film. The heat resistance of Comparative Examples 1-2, which only add siloxane and fluorinated groups respectively, shows a slight improvement, but still significantly lower than that of Examples 1-10. Comparing the results of Examples 1-6, it can be seen that the high-temperature resistance of phenolic resins formed by different phenolic and aldehyde polycondensation reactions varies. The use of salicylaldehyde and naphthol significantly increases the heat resistance. The conjugated rigid structure of the benzene ring and the polar effect of the hydroxyl group enhance the intermolecular forces. The conjugation of the benzene ring forms a stable cross-linked structure between molecules. After heat curing... Further cross-linking of phenolic resin and acrylate forms a more stable methylene structure, improving the thermal stability of the photoresist. This improved thermal stability is beneficial for the stability of the photoresist during alkaline development, preventing unexposed photoresist from being dissolved and removed by the hot alkaline solution. Comparing the results of Examples 1 and 7-8, it is clear that changing the phenolic resin molar ratio has little effect on the thermal stability of the photoresist. However, excessive salicylaldehyde leads to an increase in the free phenol content in the system, which is easily oxidized at high temperatures, affecting the photolithography process. The results of Examples 1 and 9-10 show that as the amount of modified phenolic resin increases, the heat resistance of the film gradually improves. However, the introduction of excessive modified phenolic resin reduces the adhesion of the photoresist, affecting its application in chain lithography machines and reducing the precision and resolution of the pattern.

[0052] Examples 12-19

[0053] α-Naphthol, salicylaldehyde, and modifier were dried in a vacuum drying oven at 80°C for 2 hours to obtain a dried material. 80 parts of the phenylphenol, furfural, and 20 parts of hydroxyl-terminated polydimethylsiloxane were sequentially added to a three-necked flask and heated to 50°C to mix thoroughly, thus obtaining a mixed system. 60 parts of a 30% sodium hydroxide solution were added to the mixed system and stirred for 10 minutes to obtain a reaction system. The reaction system was heated to 70°C and kept at this temperature for 5 hours to obtain a reaction product. Citric acid solution was added to the reaction product to adjust the pH to neutral, and the mixture was left overnight. After centrifugation, filtration, and washing, modified phenolic resin was obtained.

[0054] Five parts of azobisisobutyronitrile (AIBN) were added to 20 ml of deionized water and stirred at 300 rpm to obtain an emulsion. The emulsion was then added to a flask, and 0.5 parts of potassium persulfate were added at 100 rpm. Styrene acrylate, acrylic acid, and modifier II were stirred for 30 min to obtain a pre-emulsion. 0.5 parts of potassium persulfate were added to the pre-emulsion, and the mixture was stirred at 200 rpm for 20 min under nitrogen protection to obtain a mixed system. The mixed system was heated to 80°C and reacted. After blue light appeared, the temperature was maintained for 10 min to obtain a reaction system. The reaction system was heated to 90°C and maintained for 3 h to obtain a reactant. The reactant was cooled to 40°C to obtain a reaction product. The reaction product was adjusted to pH 7-8 with ammonia water, and the gel was filtered through gauze to obtain modified acrylate. The remaining preparation process was the same as in Example 1, and the specific parameters are detailed in Table 3.

[0055] Table 3. Variations in component dosage in Examples 12-18

[0056]

[0057]

[0058] Comparative Example 1 follows the same preparation method and parameters as Example 1, except that no terminal hydroxyl polydiphenylsiloxane is added.

[0059] Comparative Example 2 follows the same preparation method and parameters as Example 1, except that hexafluorophenyl methacrylate is not added.

[0060] Comparative Example 3 was prepared using the same method and parameters as in Example 1, but without the addition of terminal hydroxyl polydiphenylsiloxane and hexafluorophenyl methacrylate.

[0061] Comparative Example 4 follows the same preparation method and parameters as Example 1, but without the addition of modified nano-titanium dioxide.

[0062] Comparative Example 5 follows the same preparation method and parameters as Example 1, except that modified nano-titanium dioxide is added during the photoresist colloid preparation process.

[0063] Example 20: HF acid resistance test

[0064] The photoresists prepared in Examples 12-19 and Comparative Examples 1-5 were uniformly coated onto silicon wafer samples using an immersion method. The samples were then placed in a 0.5 mol / LDE hydrofluoric acid solution and immersed for 2 hours. The samples were then removed and the corrosion of the photoresist surface was observed using an optical microscope. The roughness parameters of the pattern edges were measured to evaluate the integrity of the photoresist. The test results are shown in Table 4.

[0065] Table 4. Hydrofluoric acid resistance test results for Examples 12-18 and Comparative Examples 1-5

[0066]

[0067]

[0068] As shown in Table 4, the photoresist prepared in Comparative Example 3 without the addition of terminal hydroxyl polydiphenylsiloxane and hexafluorophenyl methacrylate exhibits significantly reduced resistance to hydrofluoric acid corrosion compared to Example 12. The photoresists prepared in Comparative Examples 1-2 with only the addition of siloxane or fluorinated acrylate show improved corrosion resistance compared to Comparative Example 3. However, compared to Example 12, which utilizes the high hydrophobicity and reactivity of the siloxane bonds in terminal hydroxyl polydiphenylsiloxane to prevent direct reaction between hydrofluoric acid and the resin matrix, thus improving hydrofluoric acid corrosion resistance, the low surface energy of fluorine atoms in the fluorinated acrylate allows for the formation of a dense hydrophobic film on the photoresist surface. The resulting carbon-fluorine bonds effectively resist hydrofluoric acid from penetrating the photoresist and eroding the internal chemical bonds. The results of Comparative Examples 4-5 show that changes in the addition method of modified nano-titanium dioxide significantly affect the corrosion resistance of the photoresist. When the photoresist colloid is prepared, stirring is performed... Adding modified nano-titanium dioxide allows the nanoparticles to fill the voids within the resin. When subjected to hydrofluoric acid (HF) erosion, this helps disperse and consume HF. Simultaneously, the titanium dioxide occupies these voids, preventing HF from penetrating the resin structure and eroding the internal chemical bonds. Results from Examples 12-17 show that using a modifier containing conjugated groups improves HF resistance. The introduction of conjugated groups effectively adheres to the substrate surface, forming strong interfacial forces that enhance the photoresist's adhesion to the substrate. Furthermore, the relatively strong chemical inertness and the repulsive force of the conjugated system against negative fluoride ions further improve acid resistance. The rigid conjugated system of benzene rings also has stacking capabilities, forming a tight layer that synergistically fills the resin voids with nano-titanium dioxide, slowing down or preventing HF solution from penetrating the interface between the photoresist and substrate, thus achieving excellent acid resistance.

[0069] Examples 21-27 follow the same preparation methods and parameters as Example 12, with differences shown in Table 5.

[0070] Comparative Example 6 follows the same preparation method and parameters as Example 12, except that no modified acrylate is added.

[0071] Comparative Example 7 follows the same preparation method and parameters as Example 12, except that acrylic acid is not added.

[0072] Comparative Example 8 follows the same preparation method and parameters as Example 12, except that the stepwise feeding method is not used to prepare the modified acrylate.

[0073] Comparative Example 9 was prepared using the same method and parameters as in Example 12, except that only 2-hydroxy-2-methyl-1-phenylpropanone was used as the photosensitizer.

[0074] Comparative Example 10 was prepared using the same method and parameters as Example 12, except that only sodium diazonoquinone sulfonate was used as the photosensitizer.

[0075] Comparative Example 11 follows the same preparation method and parameters as Example 12, except that toluene is used as the solvent.

[0076] Comparative Example 12 follows the same preparation method and parameters as Example 12, except that isopropanol is used as the solvent.

[0077] Example 28 Adhesion Test

[0078] The silicon substrates after development in Examples 21-27 and Comparative Examples 6-12 were placed in an oven at 180°C for 10 minutes for post-baking. After cooling to room temperature, the photoresist film was scribed in a grid pattern, and then torn three times with 3M tape. The surface condition was observed to evaluate the adhesion of the photoresist to the substrate. No peeling was considered excellent; peeling area less than or equal to 5% of the scribed area was considered good; peeling area less than or equal to 15% of the scribed area was considered medium; and peeling area greater than 15% was considered poor. The test results are shown in Table 5.

[0079] Table 5 Adhesion tests of Examples 21-27 and Comparative Examples 6-12

[0080]

[0081] As shown in Table 5, the results of Examples 21 and Comparative Examples 6-8 indicate that the addition of modified acrylate significantly improves the adhesion of the photoresist. The introduction of acrylic acid increases the crosslinking sites of the modified acrylate, resulting in more polar groups during photoresist curing, increased compatibility between the modified acrylate and modified phenolic resin, improved formation of crosslinked three-dimensional structures, and enhanced adhesion between the photoresist and the silicon substrate. In Comparative Example 8, the modified acrylate directly prepared via a one-step method exhibits rapid reaction and enhanced emulsion polymerization stability due to the rapid addition of the initiator. However, an excessively fast reaction rate can lead to… The increased viscosity of acrylate latex particles leads to significant gelation, reducing monomer conversion rate. The resulting modified acrylate has high viscosity, affecting the solubility of the modified phenolic resin in propylene glycol methyl ether acetate during photoresist preparation. Furthermore, the addition of high-viscosity modified acrylate rapidly increases the viscosity of the photoresist, reducing coating uniformity and affecting adhesion between the photoresist and the substrate. Excessive viscosity also hinders solvent evaporation, causing the photoresist to remain wet on the substrate surface for an extended period, further reducing adhesion. Comparative Examples 9-10 show a significant decrease in adhesion compared to Example 21, affecting photosensitive... The addition of the agent triggers chemical reactions between groups in the photoresist. During illumination, 1,4-diazonaphthoquinone and 2-hydroxy-2-methyl-1-phenylpropanone can release more free radicals, providing more cross-linking structures and increasing adhesion. The results of Examples 12 and Comparative Examples 11-12 show that changes in solvent type further affect the adhesion of the photoresist. Toluene has poor solubility for modified acrylates, leading to reduced coating uniformity and decreased adhesion during preparation. The introduction of isopropanol reduces the solubility for modified phenolic resin, thereby reducing the cross-linking effect of the matrix resin and decreasing adhesion to the substrate. Propylene glycol methyl ether acetate is used, leveraging its high compatibility to adjust the viscosity of the photoresist. Its low surface tension also helps the photoresist better wet the substrate surface, thus improving adhesion. By using propylene glycol methyl ether acetate in conjunction with modified acrylates and adjusting the mass fraction and composition of the photosensitizer, the adhesion between the photoresist and the substrate is further enhanced. Good adhesion helps maintain the integrity of the photoresist pattern, achieving high-resolution patterns. Simultaneously, improved adhesion prevents acid from eroding the photoresist at the interface edge between the photoresist and the substrate during hydrofluoric acid etching, further improving hydrofluoric acid resistance.

[0082] Example 29

[0083] The preparation of the photoresist colloid is as described in Example 12;

[0084] Five parts of KH-792 were dissolved in 95% ethanol solution, and the pH of the system was adjusted to 3 with acetic acid. The solution was stirred in a magnetic stirrer at 50°C for 2 hours to obtain a silane coupling agent solution. Thirty parts of nano-titanium dioxide were slowly added to the silane coupling agent solution and reacted at 50°C for 2 hours to obtain a modified system. The modified system was dried at 80°C for 2 hours and ground for 30 minutes to obtain modified nano-titanium dioxide. Ten parts of the modified nano-titanium dioxide were added to 100 parts of the photoresist colloid and stirred at 300 rpm for 2 hours at 30°C. Impurity particles were removed by filtration through a 0.2 μm pore size filter membrane to obtain an alkali-soluble photoresist that is resistant to HF and can be removed by resisting photoresist removal.

[0085] Examples 30-35 follow the same preparation method and parameters as Example 29, with differences shown in Table 6.

[0086] Table 6. Differences in parameters of Examples 29-35

[0087]

[0088] Comparative Example 13 follows the same preparation method and parameters as Example 29, except that no modified nano-titanium dioxide is added.

[0089] Comparative Example 14 follows the same preparation method and parameters as Example 29, except that modified nano-titanium dioxide is added during the preparation of the photoresist colloid.

[0090] Comparative Example 15 was prepared using the same method and parameters as in Example 29, but without the addition of KH-792 for modification.

[0091] Comparative Example 16 follows the same preparation method and parameters as Example 29, but differs from the use of KH-570 modification.

[0092] Comparative Example 17 follows the same preparation method and parameters as Example 29, except that it uses modified nano-silica.

[0093] Example 36 Alkali solubility test

[0094] The photoresists prepared in Examples 30-35 and Comparative Examples 13-17 were exposed, developed, and etched with hydrofluoric acid. They were then placed in a 5% sodium hydroxide alkaline solution and kept at 50°C in a water bath. The time required for the photoresist to completely dissolve was recorded, i.e., the alkaline dissolution rate. The smoothness of the substrate surface after alkaline dissolution was observed by atomic force microscopy (AFM) to determine whether there was residual photoresist or substrate damage caused by uneven dissolution. The test results are shown in Table 7.

[0095] Table 7 Alkali solubility test of Examples 30-35 and Comparative Examples 13-17

[0096] Example Alkali dissolution rate / s Evaluation of residual photoresist Example 29 15 No obvious residue, surface clean Example 30 18 No obvious residue, surface clean Example 31 20 No obvious residue, surface clean Example 32 16 No obvious residue, surface clean Example 33 14 No obvious residue, surface clean Example 34 18 No obvious residue, surface clean Example 35 14 No obvious residue, surface clean Comparative Example 13 78 There is a significant amount of residue, posing a slight risk of damage to the substrate. Comparative Example 14 45 A small amount of residue remains, requiring a second cleaning. Comparative Example 15 58 There is a significant amount of residue, posing a slight risk of damage to the substrate. Comparative Example 16 66 There is a significant amount of residue, posing a slight risk of damage to the substrate. Comparative Example 17 75 There is a significant amount of residue, posing a slight risk of damage to the substrate.

[0097] As shown in Table 7, the photoresists prepared in Comparative Examples 13 and 17 without or with modified nano-titanium dioxide showed a significantly higher alkali solubility rate compared to Example 29 after exposure, development, and hydrofluoric acid etching, followed by alkaline solution removal. This poor alkali solubility affected the photoresist removal process, leaving photoresist residue on the surface and increasing the impact on subsequent processing. The addition of the photosensitizer caused photodegradation during exposure, generating free radicals that altered the resin's chemical bonds. This increased resin dissolution and dispersion in the solvent, enhancing alkali solubility. For unexposed resin, the filling effect of nano-titanium dioxide on resin voids and the strong intermolecular forces between resin molecules reduced solubility while preventing erosion by alkaline groups. During hydrofluoric acid etching, nano-titanium dioxide fills the voids in the resin material, increasing the photoresist's resistance to hydrofluoric acid corrosion. During etching, some titanium dioxide reacts with hydrofluoric acid, forming a dense film that further enhances resistance. After etching, the surface-reacted nano-titanium dioxide cannot fully fill the voids in the photoresist resin structure, allowing moisture and alkali molecules to penetrate and break chemical bonds, thus increasing the alkali dissolution rate. Comparative Examples 15-16 include a modifier to increase the bonding between the nano-titanium dioxide and the matrix resin. The modified material ensures a more secure filling of the nano-titanium dioxide, preventing dissolution during acid etching. Simultaneously, the addition of the modifier prevents the agglomeration of the nano-titanium dioxide, thus avoiding decreased solubility of the photoresist in alkaline solutions during alkaline dissolution, which would increase photoresist residue and affect subsequent processing. Results from Examples 29-35 show that controlling the amount of modified nano-titanium dioxide and changing the process parameters for blending photoresist and nano-titanium dioxide have minimal impact on photoresist residue, resulting in no photoresist residue on the surface. However, increasing the amount of modified nano-titanium dioxide increases the alkaline dissolution time, affecting the dissolution rate of the photoresist in alkaline solvents.

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A photoresist resistant to HF resist removal and alkali-soluble, characterized in that: The photoresist comprises a photoresist colloid and modified nano-titanium dioxide; The photoresist colloid comprises 45-75 parts of modified phenolic resin, 12-25 parts of modified acrylate, 5-15 parts of photosensitizer, 160-240 parts of solvent and emulsion additives. The modified phenolic resin is prepared by using phenolic compounds, aldehyde compounds, and modifier one; the modified acrylate is prepared by using styrene acrylate, acrylic acid, and modifier two. The first modifier is selected from one of hydroxyl-terminated polydiphenylsiloxane, hydroxyl-terminated polyphenylmethylsiloxane, and hydroxyl-terminated polydimethylsiloxane; the second modifier is selected from one of hexafluorophenylpropyl methacrylate, perfluorooctyl ethyl acrylate, and methacrylic acid. The mass ratio of the photoresist colloid to the modified nano-titanium dioxide is 8-12:1; The emulsion additives include silicone oil and antioxidant 1010.

2. The alkali-soluble photoresist resistant to HF resist removal according to claim 1, characterized in that: The phenolic compound is selected from one of α-naphthol, nonylphenol, phenol, and phenylphenol; the aldehyde compound is selected from one of salicylaldehyde, formaldehyde, and furfural; the molar ratio of the phenolic compound to the aldehyde compound is 1:1.2-1.

8.

3. The alkali-soluble photoresist resistant to HF resist removal according to claim 1, characterized in that: The mass ratio of the modified phenolic resin to the modified acrylate is 1-5:1; the solvent is propylene glycol methyl ether acetate.

4. The alkali-soluble photoresist resistant to HF resist removal according to claim 1, characterized in that: The photosensitizer is a mixture of 2-hydroxy-2-methyl-1-phenylpropanone and sodium diazonoquinone sulfonate; the mass ratio of 2-hydroxy-2-methyl-1-phenylpropanone to sodium diazonoquinone sulfonate is 1-5:

1.

5. A method for preparing an alkali-soluble photoresist resistant to HF resist removal as described in claim 1, characterized in that: The preparation of the photoresist includes the following steps: Modified phenolic resin was added to a three-necked flask, followed by propylene glycol methyl ether acetate. The resin was dissolved completely under nitrogen protection and stirring at 30°C to obtain a homogeneous solution. Modified acrylate was slowly added to the homogeneous solution, and the mixture was stirred at 300 rpm for 30 minutes to obtain a mixed solution. A photosensitive substance was slowly added to the propylene glycol methyl ether acetate, and the mixture was continuously stirred until homogeneous to obtain a dispersion. The dispersion was slowly added to the mixed solution, and the mixture was stirred until homogeneous. Silicone oil and stabilizer 1010 were then added, and the mixture was heated to 40°C and stirred for 2 hours. The mixture was filtered through a filter membrane to remove impurities, yielding a photoresist colloid. KH-792 was dissolved in 95% ethanol solution, and the pH of the system was adjusted to 3 with acetic acid. The mixture was stirred in a magnetic stirrer at 50°C for 2 hours to obtain a silane coupling agent solution. Nano-titanium dioxide was slowly added to the silane coupling agent solution, and the reaction was carried out for 2 hours to obtain a modified system. The modified system was dried and ground to obtain modified nano-titanium dioxide. The modified nano-titanium dioxide was added to the photoresist colloid, and the mixture was stirred at 200-400 rpm for 1-3 hours at 30-60°C. The mixture was then filtered through a filter membrane to remove impurities, and the photoresist was obtained.

6. The method for preparing alkali-soluble photoresist resistant to HF resist removal according to claim 5, characterized in that: The preparation of the modified phenolic resin includes the following steps: A phenolic compound, an aldehyde compound, and a modifier were dried in a vacuum drying oven at 80°C for 2 hours to obtain a dried material. The phenolic compound, aldehyde compound, and modifier were then added sequentially to a three-necked flask and heated to 50°C to mix thoroughly, thus obtaining a mixed system. A 30% sodium hydroxide solution was added to the mixed system, and the mixture was stirred for 10 minutes to obtain a reaction system. The reaction system was heated to 70°C and kept at that temperature for 5 hours to obtain a reaction product. Citric acid solution was added to the reaction product to adjust the pH to neutral, and the mixture was left overnight. After centrifugation, filtration, and washing, the modified phenolic resin was obtained. Modifier one accounted for 20% of the total mass of the phenolic resin.

7. The method for preparing alkali-soluble photoresist resistant to HF resist removal according to claim 5, characterized in that: The preparation of the modified acrylate includes the following steps: Azobisisobutyronitrile (AIBN) was added to deionized water and stirred at 300 rpm to obtain an emulsion. The emulsion was then added to a flask, and potassium persulfate was added at 100 rpm. Styrene acrylate, acrylic acid, and modifier II were stirred to obtain a pre-emulsion. Potassium persulfate was added to the pre-emulsion, and the mixture was stirred at 200 rpm for 20 min under nitrogen protection to obtain a mixed system. The mixed system was heated to 80°C and reacted. After blue light appeared, potassium persulfate was added again, and the mixture was kept at this temperature for 10 min to obtain a reaction system. The reaction system was heated to 90°C and kept at this temperature for 3 h to obtain a reactant. The reactant was cooled to 40°C to obtain a reaction product. The reaction product was added to ammonia water to adjust the pH to 7-8, and the gel was filtered through gauze to obtain the modified acrylate. The mass ratio of styrene acrylate, acrylic acid, and modifier II was 12:5:3.

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