Fluoride-free onium salt type photoacid generator, preparation method thereof and photoresist composition
By developing a fluorine-free onium salt-type photoacid generator, the environmental pollution and substrate corrosion problems of traditional photoacid generators have been solved, enabling the preparation of high-performance photoresists that meet environmental protection and performance requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUBEI THREE GORGES LAB
- Filing Date
- 2025-12-17
- Publication Date
- 2026-05-01
AI Technical Summary
Traditional fluorinated onium salt-based photoacid generators pose environmental pollution risks and substrate corrosion problems, making it difficult to meet the requirements of high photosensitivity, strong acidity, and environmental friendliness.
A fluorine-free onium salt-type photoacid generator, including thioonium salts and iodonium salts, was developed. Through specific structural design and preparation methods, a fluorine-free alkyl sulfonate onium salt photoacid generator was prepared and applied to photoresist compositions.
This photoresist achieves high resolution, good photosensitivity, excellent thermal stability, and etching resistance, while reducing environmental pollution and meeting environmental regulations.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of photosensitizer technology, specifically relating to a fluorine-free onium salt-type photoacid generator, its preparation method, and a chemically amplified photoresist composition. This onium salt type includes thioonium salt and iodonium salt types, expanding the application of fluorine-free anion design in different cationic structures. Background Technology
[0002] Photoacid generators (PAGs) are key components in photoresist compositions. They decompose under ultraviolet light or electron beams to produce acid, which triggers cross-linking or decomposition reactions in the acid-sensitive resin, enabling patterned imaging. As semiconductor manufacturing processes advance towards smaller linewidths, the performance requirements for photoacid generators are becoming increasingly stringent, including high photosensitivity, strong acidity, good solubility, and environmental friendliness.
[0003] Traditional onium salt-type photoacid generators mostly use fluoride-containing anions, such as trifluoromethanesulfonate (TfO). - Fluorinated compounds, such as perfluoroalkyl sulfonates or fluorinated alkyl sulfonates, while possessing high acid strength, pose environmental pollution risks. Fluorides may be released into the environment during production and use, leading to persistent organic pollutants (POPs), which is inconsistent with green chemistry principles. Furthermore, fluorinated photoacid generators may cause substrate corrosion or compatibility issues in certain applications. Summary of the Invention
[0004] In view of the above reasons, the purpose of this invention is to provide a fluorine-free onium salt-type photoacid generator, including thioonium salt and iodonium salt types. This onium salt photoacid generator has a stable structure, strong photosensitivity, and is free of fluorine, making it suitable for KrF and ArF wavelength photolithography processes at 248 and 193 nm. When this photoacid generator is applied to a photoresist composition, the resulting photoresist exhibits high resolution, good photosensitivity, excellent thermal stability, and etching resistance.
[0005] To achieve the above objectives, according to the first part of the present invention, a fluorine-free onium salt type photoacid generator is provided, wherein the fluorine-free onium salt type photoacid generator has the structure shown in formula ①:
[0006] X is S (sulfur) or I (iodine), and R1 and R2 each independently represent hydrogen, aryl, alkyl or heterocyclic groups.
[0007] In some preferred embodiments, R1 is hydrogen, methoxy, or isobutyl ester; R2 is isobutyl or isobutylbenzene.
[0008] In some preferred embodiments, X is S (sulfur) or I (iodine), where n is 2 when X is S and n is 1 when X is I. Furthermore, for thioonium salts: R1 is hydrogen, methoxy, isobutyl ester; R2 is isobutyl.
[0009] For iodonium salts: R1 is hydrogen, R2 is isobutyl, and phenylisobutyl.
[0010] Furthermore, the fluorine-free onium salt photoacid-generating agent is selected from at least one of the following compound structures:
[0011] To achieve the above objectives, according to the second part of the present invention, a method for preparing a fluorine-free onium salt-type photoacid generator is also provided, the method comprising: Step 1. React the corresponding starting compound (such as thionium chloride or iodonium chloride) with tetrabutylammonium dicyanamide in a solvent to generate a fluorine-free alkyl sulfonium salt photoacid generator; Step 2. The final product is obtained by purifying the onium salt photoacid generator of fluorine-free alkyl sulfonate through recrystallization.
[0012] Specifically, for thionium salts: the starting compound is triphenylthionium chloride, and the solvent is dichloromethane; the non-fluorosulfonate is tetrabutylammonium dicyanosulfonate.
[0013] The thionium cation is selected from at least one of triarylthionium, diarylalkylthionium, and aryldialkylthionium; The solvent is dichloromethane; the non-fluorosulfonate is tetrabutylammonium dicyanosulfonate; Alternatively, the iodonium cation is selected from at least one of diaryliodonium and arylalkyliodonium; The solvent is dichloromethane; the non-fluorosulfonate is tetra-n-butylammonium dicyanosulfonate.
[0014] .
[0015] X, R, n, and the aforementioned fluorine-free onium salt photoacid-generating agent have the same meanings as described above.
[0016] Further, in step 1, the molar ratio of thionium chloride or iodonium chloride to tetrabutylammonium dicyanamide sulfonate is 1:1-1.5, more preferably 1:1.2; the reaction temperature is 25-40℃, more preferably 30℃; and the reaction time is 18-24h, more preferably 20h.
[0017] Furthermore, in step 2, the preferred recrystallization solvent combination is dichloromethane / methanol, chloroform / methanol, tetrahydrofuran / methanol, ethyl acetate / petroleum ether, acetone / petroleum ether, or dioxane / methanol. According to the third part of the present invention, the application of the aforementioned fluorine-free onium salt type photoacid generator in a photoresist composition is also provided, the composition comprising an acid-sensitive resin, a photoacid generator and a solvent, wherein the amount of photoacid generator added is 1-10 wt% of the resin mass.
[0018] The amount of fluorine-free onium salt-type photoacid generator added is 1-10 wt% of the resin mass; The acid-sensitive resin is selected from at least one of poly(4-hydroxystyrene) and its derivatives, acrylate resins, and cyclic olefin maleic anhydride copolymers; The solvent is selected from at least one of propylene glycol monomethyl ether acetate, ethyl lactate, cyclohexanone, and γ-butyrolactone.
[0019] The photoresist composition is suitable for photolithography processes with wavelengths of 248 nm or 193 nm.
[0020] The present invention also provides a photolithography process, in which the photoresist composition is used for coating, exposure, post-baking and development; the exposure wavelength is 248 nm or 193 nm.
[0021] The present invention utilizes the solution provided in this application, employing the fluorine-free onium salt-type photoacid generator, its preparation method, and a photoresist composition. By applying this photosensitive compound to the photoresist composition, the resulting photoresist exhibits high resolution, good photosensitivity, excellent thermal stability, and etching resistance. The fluorine-free photoacid generator product reduces environmental pollution and complies with environmental regulations. Detailed Implementation
[0022] The technical solution of the present invention will be further explained and described below with reference to specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the contents of the claims. Modifications and substitutions made by those skilled in the art to the technical solution of the present invention without creative effort all fall within the scope of protection of the present invention.
[0023] The present invention will be further illustrated by specific embodiments below, but is not limited thereto.
[0024] Example 1: Preparation of Triarylthionium Dicyanosulfonate
[0025] 10 g of triarylthionium chloride and 13 g of tetrabutylammonium dicyanamide sulfonate were dissolved in 50 mL of dichloromethane and stirred at 30 °C for 20 hours. After the reaction was completed, the solvent was evaporated, and the product was purified by recrystallization to give 11 g of white solid product, with a yield of 85%.
[0026] The product was characterized by NMR:1 H NMR (CDCl3) δ 7.36 (m, 3H), 7.30 (m, 6H), 7.28 (m, 6H); 13 C NMR (CDCl3) δ 143.3, 125.4, 128.7, 117.8; UV-vis: λ max =243 nm.
[0027] Example 2: Preparation of (isobutylbenzene)dibenzothiophene thioonium dicyanosulfonate
[0028] 12 g of (isobutylbenzene) dibenzothiophene thionium was dissolved in 50 mL of dichloromethane and stirred at room temperature for 20 hours. After the reaction was completed, the solvent was evaporated, and the product was purified by recrystallization to give 13 g of white solid product, with a yield of 76%.
[0029] The product was characterized by NMR: 1 H NMR (CDCl3) δ 7.78(d, 2H), 7.6 (d, 2H), 7.51 (m, 2H), 7.31 (d, 2H), 7.25 (d, 2H), 1.33 (s, 9H); 13 C NMR (CDCl3) δ 151.3, 145.1, 140.2, 136.4, 132.8, 127.6, 125.9, 125.0, 122.6, 117.8, 34.2. UV-vis:λ max =246 nm.
[0030] Example 3: Preparation of diaryliodonium dicyanosulfonate
[0031] 15 g of diphenyl sulfide was dissolved in 50 mL of dichloromethane and stirred at room temperature for 20 hours. After the reaction was complete, the solvent was evaporated, and the product was purified by recrystallization to give 18 g of white solid product, with a yield of 79%.
[0032] The product was characterized by NMR: 1 H NMR (CDCl3) δ 8.27 (d, 2H), 7.83 (s, 2H), 7.67 (m, 2H); 13 C NMR (CDCl3) δ 135.2, 132.1, 131.4, 120.6, 117.8. UV-vis:λ max =250 nm.
[0033] Example 4: Preparation of diisobutylbenzeniodonium dicyanosulfonate
[0034] 20 g of diisobutylbenzeneiodonium salt was dissolved in 50 mL of dichloromethane and stirred at room temperature for 24 hours. After the reaction was completed, the solvent was evaporated, and the product was purified by recrystallization to give 22 g of white solid product, with a yield of 77%.
[0035] The product was characterized by NMR: 1 H NMR (CDCl3)δ 8.19 (d, 2H), 7.31 (d, 2H), 1.33 (s,9H); 13 C NMR (CDCl3) δ 151.3, 134.8, 125.0, 117.5, 34.2. UV-vis:λ max =246 nm.
[0036] Example 5: Preparation and testing of photoresist composition based on the product of Example 1 Take 100g of poly(4-hydroxystyrene) resin, add 5g of the product from Example 1 as a photoacid-generating agent, dissolve in 500mL of propylene glycol monomethyl ether acetate (PGMEA), and stir until homogeneous. Coat onto a silicon wafer, pre-bake at 90℃ / 60s, and expose (248nm, 20mJ / cm²). 2 After baking at 120℃ for 60 seconds, develop. Test results: resolution 50nm, LER 4.2nm.
[0037] Example 6: Preparation and testing of photoresist composition based on the product of Example 2 Take 100g of poly(4-hydroxystyrene) resin, add 5.5g of the product from Example 2 as a photoacid-generating agent, dissolve in 500mL of propylene glycol monomethyl ether acetate (PGMEA), and stir until homogeneous. Coat onto a silicon wafer, pre-bake at 90℃ / 60s, and expose (248nm, 20mJ / cm). 2 After baking at 120℃ for 60 seconds, develop. Test results: resolution 65nm, LER 5.5nm.
[0038] Example 7: Preparation and testing of photoresist composition based on the product of Example 3 Take 100g of poly(4-hydroxystyrene) resin, add 3.5g of the product from Example 3 as a photoacid-generating agent, dissolve in 500mL of propylene glycol monomethyl ether acetate (PGMEA), and stir until homogeneous. Coat onto a silicon wafer, pre-bake at 90℃ / 60s, and expose (248nm, 20mJ / cm²). 2 After baking at 120℃ for 60 seconds, develop. Test results: resolution 58 nm, LER 4.8 nm.
[0039] Example 8: Preparation and testing of photoresist composition based on the product of Example 4 Take 100g of poly(4-hydroxystyrene) resin, add 3.5g of the product from Example 3 as a photoacid-generating agent, dissolve in 500mL of propylene glycol monomethyl ether acetate (PGMEA), and stir until homogeneous. Coat onto a silicon wafer, pre-bake at 90℃ / 60s, and expose (248nm, 20mJ / cm²). 2 After baking at 120℃ for 60 seconds, develop. Test results: resolution 50 nm, LER 4.5 nm.
[0040] Example 9: Thermal stability and acid strength test The four fluorine-free thionium salts from Examples 1-4 were subjected to TGA tests under a nitrogen atmosphere. The 5% weight loss temperatures were 230, 232, 220, and 218, respectively, which are higher than those of the traditional triphenylthionium perfluorooctane sulfonate (198 °C).
[0041] The pKa values of the photogenerated acid were measured using the Hammett indicator method to be -2.1, -2.3, -2.6, and -2.8, respectively. The acid strength is comparable to that of trifluoromethanesulfonic acid, but it contains no fluorine at all.
[0042] Example 9: Environmental friendliness assessment Photoresist prepared using the product of Example 1 showed a fluorine content of <0.05 at% and a biodegradation rate of >90% (OECD test after 28 days), which is far superior to fluorinated PAG (degradation rate <50%). Comparative Example 1: Traditional Fluorosulfonium Salts Using triphenylthionium trifluoromethane sulfonate as a comparison, the test results under the same conditions showed a resolution of 55 nm, an LER of 6.5 nm, and an environmental assessment indicating a fluorine release of >10 ppm.
[0043] Comparative Example 2: Traditional Fluoride-Iodonium Salt Comparison using diphenyliodonium trifluoromethane sulfonate: resolution 50 nm, LER 5.1 nm, fluorine release >15 ppm.
[0044] The above embodiments fully demonstrate that the fluorine-free onium salt-type photoacid generators (including thioonium salts and iodonium salts) provided by the present invention exhibit excellent sensitivity, resolution, LER and environmental friendliness at various advanced lithography nodes such as KrF and ArF, and have extremely strong prospects for industrial application.
Claims
1. A fluorine-free onium salt-type photoacid-generating agent, characterized in that, The fluorine-free onium salt type photoacid generator has the structure shown in formula ①: Formula ① Where X is S or I, and n is an integer from 1 to 2; R1 and R2 each independently represent hydrogen, aryl, alkyl, or heterocyclic groups.
2. The fluorine-free onium salt type photoacid-generating agent according to claim 1, characterized in that, R1 is hydrogen, methoxy, or isobutyl ester; R2 is isobutyl or isobutylbenzene.
3. The method for preparing the fluorine-free onium salt type photoacid generator according to claim 1 or 2, characterized in that, The preparation method includes: Step 1. React the corresponding starting compound thionium chloride or iodonium chloride with tetrabutylammonium dicyanamide in a solvent to generate a fluorine-free alkyl sulfonium salt photoacid generator; Step 2. The final product is obtained by purifying the onium salt photoacid generator of fluorine-free alkyl sulfonate through recrystallization.
4. The preparation method of the fluorine-free onium salt type photoacid generator according to claim 3, characterized in that, In step 1, the molar ratio of thionium chloride or iodonium chloride to tetrabutylammonium dicyanamide sulfonate is 1:1-1.5, more preferably 1:1.2; the reaction temperature is 25-40℃, more preferably 30℃; and the reaction time is 18-24h, more preferably 20h.
5. The preparation method of the fluorine-free onium salt type photoacid generator according to claim 3, characterized in that, In step 2, the preferred recrystallization solvent combination is dichloromethane / methanol, chloroform / methanol, tetrahydrofuran / methanol, ethyl acetate / petroleum ether, acetone / petroleum ether, or dioxane / methanol.
6. The preparation method of the fluorine-free onium salt type photoacid generator according to claim 3, characterized in that, The thionium cation is selected from at least one of triarylthionium, diarylalkylthionium, and aryldialkylthionium; The solvent is dichloromethane; the non-fluorosulfonate is tetrabutylammonium dicyanosulfonate; Alternatively, the iodonium cation is selected from at least one of diaryliodonium and arylalkyliodonium; The solvent is dichloromethane; the non-fluorosulfonate is tetra-n-butylammonium dicyanosulfonate.
7. A photoresist composition, characterized in that, The composition comprises the fluorine-free onium salt type photoacid generator as described in claim 1 or 2, an acid-sensitive resin, and a solvent.
8. The photoresist composition according to claim 7, characterized in that, The amount of fluorine-free onium salt-type photoacid generator added is 1-10 wt% of the resin mass; The acid-sensitive resin is selected from at least one of poly(4-hydroxystyrene) and its derivatives, acrylate resins, and cyclic olefin maleic anhydride copolymers; The solvent is selected from at least one of propylene glycol monomethyl ether acetate, ethyl lactate, cyclohexanone, and γ-butyrolactone.
9. The photoresist composition according to claim 8, characterized in that, The photoresist composition is suitable for photolithography processes with wavelengths of 248 nm or 193 nm.
10. A photolithography process, characterized in that, The photoresist composition according to any one of claims 7-9 is used for coating, exposure, post-baking, and development.