Purification method of electronic-grade sulfonium salt photoacid generator

Abstract

The invention relates to a method for purifying an electronic-grade sulfonium salt photoacid generator. The method comprises the following steps: heating, preparing a photoacid generator stock solution, purifying through ion exchange resin, cooling, recrystallizing, carrying out solid-liquid separation, washing crystals and the like to obtain the high-purity photoacid generator, so that the metal content in the photoacid generator can be effectively reduced, the single metal content is less than 5ppb, and the yield is up to 80-90%. And mother liquor is collected and purified by resin and can be used for preparing photoacid stock solution again. The operation effectively reduces the use of an organic solvent and the generation of wastewater, can further improve the recrystallization yield, and meets the requirements of green and sustainable development.

Description

Technical Field

[0001] This invention relates to the field of photoresists, and more specifically to a purification method for electronic-grade thionium salt-based photoacid generators. Background Technology

[0002] Photoresist's main components are resin, photoacid generator (PAG), and corresponding additives and solvents. The photoacid generator is the core component of photoresist; it decomposes under light to produce strong acids. These strong acids can cause decomposition and cross-linking of acid-sensitive resins or acid-instable groups. Photoacid generators are structurally classified into ionic and non-ionic types. Ionic types include thioonium salts and iodonium salts, while non-ionic types include imine sulfonates and oxime sulfonates. Thionium salt photoacid generators are widely used in chemically amplified photoresists due to their high acid-generating efficiency and good thermal stability.

[0003] As shown in the structural formula below, the current mainstream synthesis method for thionium salt-type photoacid generators is an ion exchange reaction. For example, sulfonic acid anions typically first form salts with metals such as sodium, potassium, magnesium, and lithium. After ion exchange, photoacid and the corresponding salt are generated. The residue of these metal salts can cause the content of metals such as sodium, potassium, magnesium, and lithium in the photoacid to rise to hundreds or even thousands of ppm, which are difficult to remove later, affecting wafer yield and even damaging the wafer. Therefore, reducing the residual metals in photoacid generators is crucial.

[0004] . Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a purification method for thionium salt-based photoacid-generating agents, which mainly uses a combination of ion exchange and recrystallization to reduce the single metal content in the photoacid to below 5 ppb.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: S1: Preparation of stock solution: Dissolve the photoacid in a solvent, heat to 50-60℃, and prepare a 20%-30%wt solution.

[0007] S2: Ion exchange: The sample solution is passed through a jacketed ion exchange column at a temperature of 50-70℃ to remove metals and obtain a purified solution.

[0008] S3: Cooling and crystallization: Slowly cool the purified solution to allow crystals to precipitate.

[0009] S4: Solid-liquid separation and crystal washing: The slurry in S3 is filtered, the crystals are washed with cold water, and dried to obtain an electronic-grade photoacid generator.

[0010] Furthermore, the solvent in S1 is selected from one of water, methanol, ethanol, isopropanol, acetonitrile, and ethyl acetate.

[0011] Furthermore, thionium salt-type photoacid generators have poor solubility but high thermal stability, generally decomposing after 120°C. Increasing the temperature can improve their solubility in solvents. Considering both temperature and solubility, the temperature was raised to 50-60°C for dissolution.

[0012] Preferably, the concentration in S1 is configured as 20%wt, 25%wt, or 30%wt.

[0013] Furthermore, the ion exchange resin in S2 is a strong acid cation exchange resin. Preferably, the strong acid cation exchange resin is ORLITE 15JS-HG, Amberlite IR120H, SEPLITE SC130IND, Trilite SPC320H, or Tulsimer T-62MP.

[0014] Further, the resin pretreatment operation in S2 is as follows: the resin is rinsed with pure water in a beaker, packed into the chromatography column, and rinsed with pure water until the conductivity of the effluent is close to that of pure water. Then, the resin is rinsed with the solvent in S1 until the resin layer level no longer decreases, thus completing the resin pretreatment.

[0015] Furthermore, the flow rate through the column in S2 is 2~4 Bv / h.

[0016] Furthermore, in S4, the volume of water used to wash the crystals is 10% to 20% of the crystal mass, and to prevent the photoacid-generating agent from redissolving in the solvent, the water needs to be cooled to -5 to 5°C beforehand.

[0017] Furthermore, the thionium salt photoacid-generating agent comprises any one of the following structural formulas:

[0018] R1 and R2 each independently represent a C1-C6 alkyl or aromatic hydrocarbon group, wherein one or more hydrogen atoms in the C1-C6 alkyl or aromatic hydrocarbon group may be substituted by a hydroxyl, alkoxy, or C1-C6 alkyl group; R3 is a hydrocarbon group or a C6-C10 aromatic hydrocarbon group, wherein one or more hydrogen atoms in the hydrocarbon group or C6-C10 aromatic hydrocarbon group may be substituted by a fluorine atom.

[0019] Furthermore, the thionium salt photoacid-generating agent described herein has the following structure:

[0020] In some preferred embodiments, the technical solution of the present invention further includes mother liquor purification, that is, the mother liquor separated in S4 is passed through the resin in S2 again, and the purified mother liquor can continue to be used as a solvent in S1.

[0021] The advantages of this invention are: 1. The method of this invention combines ion exchange and recrystallization to effectively reduce the metal content in photo-induced acid-producing agents, with a yield as high as 80%-90%, and can achieve a single metal content of less than 5 ppb, meeting industry requirements.

[0022] 2. By purifying and reusing the mother liquor, the use of organic solvents and the generation of wastewater are effectively reduced, which meets the requirements of green and sustainable development. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following.

[0024] Example 1 S1: Dissolve photoacid a in ultrapure water and heat to 60°C to prepare a 30%wt solution.

[0025] S2: Add the sample solution to the pretreated strong acid cation exchange resin ORLITE 15JS-HG via a peristaltic pump at a flow rate of 3 Bv / h.

[0026] S3: Cool the purified solution in S2 by 10°C per hour. During the cooling process, crystals are observed to slowly precipitate out until the solution is cooled to 5°C.

[0027] S4: After solid-liquid separation, the crystals were washed with cold water at 20% of their mass. After drying, the metal content of the sample was tested by ICP-MS, with a yield of 85%. The metal content is shown in Table 1.

[0028] Comparative Example 1 The method is the same as in Example 1, except that the resin is replaced with ZGC151, and the metal content of the product is higher than 5 ppb.

[0029] Comparative Example 2 The method is the same as in Example 1, except that the resin is replaced with Lewatit SP112H, and the metal content of the product is higher than 5 ppb.

[0030] Comparative Example 3 The method is the same as in Example 1, except that the resin is replaced with Amberlite HPR110 Na, and the metal content of the product is higher than 5 ppb.

[0031] Comparative Example 4 The method is the same as in Example 1, except that the purified solution in S2 is cooled to 5°C within one hour, and the metal content of the product is higher than 5 ppb. Comparative Example 5 The method is the same as in Example 1, except that the photoacid in S1 is prepared into a 35%wt solution, and the metal content of the product is higher than 5 ppb.

[0032] Comparative Example 6 The method is the same as in Example 1, but the photoacid in S1 is prepared into a 15% wt solution with a yield of 68%.

[0033] Table 1. Metal ion content of the samples to be tested

[0034] Example 2 S1: Dissolve photoacid b in ethanol, heat to 55°C, and prepare a 25%wt solution.

[0035] S2: Add the sample solution to the pretreated strong acid cation exchange resin Amberlite IR120H via a peristaltic pump at a flow rate of 3 Bv / h.

[0036] S3: Cool the purified solution in S2 by 10°C per hour. During the cooling process, crystals are observed to slowly precipitate out until the solution is cooled to 5°C.

[0037] S4: After solid-liquid separation, the crystals were washed with cold water at 20% crystal mass. After drying, the metal content of the sample was tested by ICP-MS, with a yield of 82%.

[0038] Example 3 S1: Dissolve photosensitive acid c in isopropanol, heat to 55°C, and prepare a 20%wt solution.

[0039] S2: Add the sample solution to the pretreated strong acid cation exchange resin SEPLITE SC130IND via a peristaltic pump at a flow rate of 3 Bv / h.

[0040] S3: Cool the purified solution in S2 by 10°C per hour. During the cooling process, crystals are observed to slowly precipitate out until the solution is cooled to 5°C.

[0041] S4: After solid-liquid separation, the crystals were washed with cold water at 20% of their mass. After drying, the metal content of the sample was determined by ICP-MS, with a yield of 86%. Example 4 S1: Dissolve photoacid d in isopropanol, heat to 50°C, and prepare a 20%wt solution.

[0042] S2: Add the sample solution to the pretreated strong acid cation exchange resin Trilite SPC320H via a peristaltic pump at a flow rate of 3 Bv / h.

[0043] S3: Cool the purified solution in S2 by 10°C per hour. During the cooling process, crystals are observed to slowly precipitate out until the solution is cooled to 5°C.

[0044] S4: After solid-liquid separation, the crystals were washed with cold water at 20% of their mass. After drying, the metal content of the sample was tested by ICP-MS, with a yield of 89%.

[0045] Example 5 S1: Dissolve photoacid e in acetonitrile, heat to 55°C, and prepare a 20%wt solution.

[0046] S2: Add the sample solution to the pretreated strong acid cation exchange resin, Tulsimer T-62MP, via a peristaltic pump at a flow rate of 3 Bv / h.

[0047] S3: Cool the purified solution in S2 by 10°C per hour. During the cooling process, crystals are observed to slowly precipitate out until the solution is cooled to 5°C.

[0048] S4: After solid-liquid separation, the crystals were washed with cold water at 20% crystal mass. After drying, the metal content of the sample was tested by ICP-MS, with a yield of 83%.

[0049] Example 6 S1: Dissolve photoacid f in ethyl acetate, heat to 55°C, and prepare a 25%wt solution.

[0050] S2: Add the sample solution to the pretreated strong acid cation exchange resin SEPLITE SC130IND via a peristaltic pump at a flow rate of 3 Bv / h.

[0051] S3: Cool the purified solution in S2 by 10°C per hour. During the cooling process, crystals are observed to slowly precipitate out until the solution is cooled to 5°C.

[0052] S4: After solid-liquid separation, the crystals were washed with cold water at 20% of their mass. After drying, the metal content of the sample was tested by ICP-MS, with a yield of 90%.

[0053] The results of the obtained metal ion content are shown in Table 2.

[0054] Table 2 Metal ion content of the samples to be tested .

Claims

1. A method for purifying an electronic grade sulfonium salt-based photoacid generator, characterized by, The purification method comprises the following steps: S1: preparing a stock solution: dissolving an acid generator in a solvent, heating to 50-60℃, and preparing a 20%-30%wt solution; S2: ion exchange: passing the solution of S1 through an ion exchange resin column to remove metal ions and obtain a purified solution; S3: cooling and crystallization: slowly cooling and crystallizing the purified solution, filtering, washing, and drying to obtain an electronic-grade photoacid generator.

2. The purification method of the electronic grade sulfonium salt-based photoacid generator according to claim 1, characterized by, The solvent in S1 is selected from one of water, methanol, ethanol, isopropanol, acetonitrile, and ethyl acetate.

3. The purification method of an electronic grade sulfonium-based photoacid generator according to claim 1, characterized in that, The concentration in S1 is 20%wt, 25%wt, or 30%wt.

4. The purification method of an electronic grade sulfonium-based photoacid generator according to claim 1, characterized by, The ion exchange resin in S2 is a strong acid cation resin, and the strong acid cation resin is any one of ORLITE 15JS-HG, Amberlite IR120H, SEPLITE SC130IND, Trilite SPC320H, and Tulsimer T-62MP.

5. The purification method of an electronic grade sulfonium-based photoacid generator according to claim 1, characterized in that, The ion exchange resin in S2 is washed with water and then rinsed with the solvent in S1 until the resin layer liquid level no longer decreases, i.e., the resin pretreatment is completed.

6. The purification method of an electronic grade sulfonium photoacid generator according to claim 1, characterized by, The column flow rate in S2 is 2-4Bv / h.

7. The purification method of an electronic grade sulfonium photoacid generator according to claim 1, characterized by, The column temperature is 50-70℃.

8. The purification method of an electronic grade sulfonium-based photoacid generator according to claim 1, characterized by, The water used to wash the crystals in S3 is cooled to -5-5℃.

9. The purification method of an electronic grade sulfonium-based photoacid generator according to claim 1, characterized in that, The sulfonium salt photoacid generator comprises any one of the following structural formulas: R1, R2 each independently represents a C1-C6 alkyl group or an aromatic hydrocarbon group, one or more hydrogen atoms in the C1-C6 alkyl group or the aromatic hydrocarbon group can be substituted with a hydroxyl group, an alkoxy group, or a C1-C6 alkyl group; R3 is a hydrocarbon group or a C6-C10 aromatic hydrocarbon group, one or more hydrogen atoms in the hydrocarbon group or the C6-C10 aromatic hydrocarbon group can be substituted with a fluorine atom.

10. The purification method of the electronic-grade sulfonium salt photoacid generator according to claim 9, wherein the sulfonium salt photoacid generator has any one of the following structural formulas: ​ 。

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