Electronic grade perfluorohexylsulfonic acid, its preparation method and its use in top anti-reflective coatings for photoresists

Abstract

The application discloses electronic-grade perfluorohexyl sulfonic acid, a preparation method thereof and application of the electronic-grade perfluorohexyl sulfonic acid in a photoresist top anti-reflective film, and the electronic-grade perfluorohexyl sulfonic acid is obtained by removing impurities from commercially available perfluorohexyl sulfonic acid. The perfluorohexyl sulfonic acid is difficult to handle and is complex. The required E4-grade product can be obtained by skillfully utilizing resin primary purification and electrolytic fine purification, and can be used for preparing the photoresist top anti-reflective film. Further, the resin is electrolytically purified, and when electrolytic impurity removal of the perfluorohexyl sulfonic acid is performed, the perfluorohexyl sulfonic acid is placed into an anode chamber and used for adsorbing calcium ions, sodium ions and other metal impurity ions with high content. After electrolysis is finally completed, the calcium ions, the sodium ions and other metal ions in the product can all be controlled to be below 1 ppb, and meet the E3 standard in GB / T41881-2022, thereby further improving the added value of the product on the basis of meeting the customer use standard.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photoetching technology, and specifically relates to electronic-grade perfluorohexyl sulfonic acid, a preparation method thereof, and application of the electronic-grade perfluorohexyl sulfonic acid in a top anti-reflective film of a photoresist. BACKGROUND

[0002] Photoetching technology is a method for transferring a semiconductor circuit pattern on a photo mask to a silicon wafer, and the pattern transfer is completed by changing the material properties of a photosensitive substance on a wafer due to photosensitivity through laser or electron beam irradiation of a photo mask template.

[0003] The existing photoetching technology has the technical problem of light scattering, resulting in low size precision of photoresist imaging. The mainstream solution at present is to add a top anti-reflective film formed by a fluorine-containing compound with low refractive index and high transmittance before and after photoresist coating, so as to reduce the interference of light in the photoresist and prevent the change of photoetching line width due to the change of photoresist thickness. The composition for forming the top anti-reflective film for photoetching in the prior art still has certain deficiencies in processability, film formability, refractive index, coating amount or raw material cost.

[0004] Based on the above, the patent CN114035405B discloses a composition for preparing a top anti-reflective film for photoresist, a top anti-reflective film for photoresist and a fluorine-containing composition, which indicates that the part of the photoresist irradiated by a specific light source undergoes a photochemical reaction to produce H + When the pH value of the top anti-reflective layer is large, the generated hydrogen ions diffuse to the anti-reflective layer, the hydrogen ions in the irradiated photoresist area decrease, and the development is not complete. During the development process, the developer cannot be completely removed, thereby forming a T-shaped top, resulting in light scattering and standing wave effect in the photoetching process; and the addition of an appropriate amount of acid in the top anti-reflective layer system can inhibit the diffusion of H + to the anti-reflective film and avoid the formation of a T-shaped top. The addition amount of the acid is usually preferably 0.5-3wt% based on the total weight of the composition for preparing the top anti-reflective film, the composition has good stability and film formability, and can be coated in a small amount to form an anti-reflective film with performance comparable to that in the prior art, the refractive index of the anti-reflective film at 248nm is 1.41-1.44, the refractive index under the irradiation of a wavelength 248nm laser can be effectively reduced, and the anti-reflective film can be used as a top anti-reflective film for photoresist.

[0005] The above patent first mentioned that the addition of an appropriate amount of acid in the top anti-reflective layer system can inhibit the diffusion of H +The acid pH adjuster is selected as perfluorohexylsulfonic acid (Example 6), and the content of perfluorohexylsulfonic acid is generally preferably 0.5-3 wt%. However, perfluorohexylsulfonic acid used in the semiconductor industry has strict requirements on the content of impurity metal ions and the number of particles therein. There is little information on perfluorohexylsulfonic acid at present, and the field is basically blank. The content of impurity metal ions and the number of particles in the generally commercially available perfluorohexylsulfonic acid are quite high, and it cannot be used for compounding to prepare the top anti-reflective film of the photoresist. Therefore, it is necessary to purify the perfluorohexylsulfonic acid and reduce the number of particles therein, and reduce the total amount of metal impurities to the requirements of the customer. In addition, in GB / T41881-2022, the standard of electronic grade sulfuric acid is divided into E1, E2, E3, E4, E5, a total of 5 standards. The customer requires that the metal ions in the perfluorohexylsulfonic acid provided by the applicant meet the metal ion requirements of E1, E2, E3, and E4 levels of the E1, E2, E3, E4 levels of the electronic grade sulfuric acid standard, and preferably reach the E1 level. The higher the level, the higher the added value. Therefore, it has great technical and economic significance to control the metal ions in perfluorohexylsulfonic acid to a high level for compounding the top anti-reflective film.

[0006] At present, there are the following difficulties in removing impurity metal ions from perfluorohexylsulfonic acid:

[0007] Perfluorohexylsulfonic acid has a long carbon chain and a large molecular weight, and high-concentration perfluorohexylsulfonic acid has very high viscosity, which leads to few methods for removing metal ions from perfluorohexylsulfonic acid through carbon purification, and the effect of traditional purification methods is very small. For example, rectification. Generally speaking, rectification is the best method for purifying liquids, but when perfluorohexylsulfonic acid is purified by rectification, after the solvent water is evaporated, a gel-like solid perfluorohexylsulfonic acid is formed, which cannot be purified by rectification again, resulting in a high content of metal ions therein. In addition, the applicant has tried ion exchange method, freezing method, rectification method, salt transfer purification method, and high molecular adsorbent adsorption method to treat perfluorohexylsulfonic acid, but none of them has a good purification effect. The content of a single impurity metal ion still cannot meet the minimum requirements of the customer (E4 level in GB / T41881-2022).

[0008] Based on the above, the applicant uses a combination of resin impurity removal and electrolysis impurity removal to prepare electronic-grade perfluorohexylsulfonic acid, but there are still the following problems:

[0009] (1) Commercially available electronic grade resin adopts conventional acid washing method to replace all ions in the resin with hydrogen ions. But even if electronic grade strong acid such as electronic grade sulfuric acid, electronic grade hydrochloric acid, electronic grade hydrofluoric acid and the like is used to wash the resin for a long time and multiple cycles, although the metal ions in the acid solution after each washing will increase, due to the limited ability of washing treatment under acidic conditions to replace the metal ions in the resin structure with hydrogen ions, there will always be a certain amount of sodium ions in the resin, and when such resin is used to treat perfluorohexyl sulfonic acid, the sodium ion content in the obtained perfluorohexyl sulfonic acid solution is relatively high, between 100-200 ppb, which cannot meet the use requirements of the acid regulator in the preparation process of the top anti-reflective film of the photoresist.

[0010] (2) Unlike conventional inorganic acids, the perfluorohexyl sulfonic acid treated in the present application is an organic acid and has a carbon-fluorine bond in the backbone structure, and the high viscosity characteristic increases the difficulty and complexity of its treatment. During the treatment process, the applicant found that when the temperature of the solution is relatively low, due to the high viscosity and the presence of carbon-fluorine bond, the impurity ions move slowly, and the impurity ion content in the perfluorohexyl sulfonic acid obtained after multiple electrolysis is still high, and the impurity removal effect is general. When the temperature of the solution is relatively high, the electrolysis rate and ion movement speed up, which also leads to the continuous precipitation of impurity ions in the electrode plate, and also makes the impurity ion content in the perfluorohexyl sulfonic acid obtained after multiple electrolysis still high. In addition, perfluorohexyl sulfonic acid is a surfactant, and when the temperature is relatively high, the electrode chamber foams seriously, which can easily cause the tank to overflow; in addition, the foam will react after contacting the electrode clamp, causing the perfluorohexyl sulfonic acid in the electrode chamber to turn green, which further increases the difficulty of treatment.

[0011] (3) After electrolysis, the selected electrode plate under the action of acid and electrolysis will continuously precipitate metal impurity ions to pollute the product, so that the content of metal ions in the product is maintained at a certain level and cannot be reduced, but the content of calcium ions and sodium ions will continuously increase to close to 10ppb, finally the content of metal ions in the obtained product can only reach the minimum standard E4 standard or cannot reach the standard, and the product has a high rework rate. In addition, even if high-purity inert anode plates are used, the problem of calcium ions and sodium ions continuously precipitating from the anode plate into the product under the action of electricity and strong acid conditions cannot be solved. Based on this, the applicant tried to use high-purity graphite inert electrode plates as anode and cathode for electrolysis, but after long-time electrolysis, the graphite anode plate will drop slag and crack, and the graphite small black slag will enter the product liquid, thereby affecting the purity of the product. Subsequently, the applicant uses high-purity iridium tantalum titanium electrode plates and high-purity platinum gold electrode plates to replace the high-purity graphite electrode plates, which solves the problem of electrode plate slag dropping and polluting the product liquid, but still has the problem that the content of calcium ions and sodium ions in the product after electrolysis is close to 10ppb, and finally the content of metal ions in the obtained product can only reach the minimum standard E4 standard or cannot reach the standard. In addition, since the high-purity iridium tantalum titanium electrode plates and the high-purity platinum gold electrode plates are expensive, and the use of high-purity iridium tantalum titanium electrode plates and high-purity platinum gold electrode plates as anode and cathode will greatly increase the initial investment cost. SUMMARY

[0012] The purpose of the present application is to provide an electronic grade perfluorohexyl sulfonic acid with the content of single impurity metal ions reaching at least E4 level, which is used as an acid regulator in a top anti-reflective film of a photoresist.

[0013] Another purpose of the present application is to provide a preparation method of the above-mentioned electronic grade perfluorohexyl sulfonic acid.

[0014] To achieve the purpose, the present application adopts the following technical solutions:

[0015] A preparation method of an electronic grade perfluorohexyl sulfonic acid, comprising the following steps:

[0016] (1) The perfluorohexyl sulfonic acid is diluted with electronic grade pure water to a mass fraction of 1.5-3%. The perfluorohexyl sulfonic acid has a large molecular weight, and a too high concentration has a too large viscosity, which cannot pass through the resin purification. In addition, a too high concentration has a too strong acidity, and the resin cannot play a primary purification effect. Generally, when the concentration is higher than 3%, the ions adsorbed on the resin will be eluted into the solution, resulting in a poor impurity removal effect. If the impurity removal in the front-end primary purification does not reach the required range, the subsequent electrolysis cannot obtain electronic grade perfluorohexyl sulfonic acid meeting the requirements. Moreover, the electrolysis is not the more the better. The applicant verifies through experiments that after too many times of electrolysis, the contents of calcium ions and sodium ions in the electrode plate will exceed 10 ppb, which cannot meet the requirements of the customer. Therefore, only when the front-end treatment is good and the electrolysis is limited in times, can the product meet the customer's requirements;

[0017] (2) The electronic grade hydrofluoric acid is diluted with electronic grade pure water to a mass fraction of 3-6%;

[0018] (3) The hydrogen type cation resin is loaded into an ion exchange column, and then the diluted electronic grade hydrofluoric acid in step (2) is used for countercurrent washing, and then electronic grade pure water is used for cocurrent washing until the pH of the washing water is 6-7;

[0019] (4) The diluted perfluorohexyl sulfonic acid in step (1) is purified by the ion exchange resin treated in step (3), and the primary purified perfluorohexyl sulfonic acid is obtained by preferably continuously purifying twice, wherein the metal ions and their contents are as follows, unit: ppb;

[0020] Al Ba Ca Cd Co Cr Cu Fe K Mg Mn Na Zn Ni ≤6 ≤4 ≤9 ≤1 ≤3 ≤4 ≤2 ≤4 ≤10 ≤6 ≤4 ≤200 ≤5 ≤7

[0021] (5) The electrolytic cell and each component (anode chamber, anode plate, cathode chamber, cathode plate and intermediate separator membrane) are washed with electronic grade pure water until the content of all metal ions in the washing water is less than 1 ppb;

[0022] The primary purified perfluorohexyl sulfonic acid in step (4) is placed in the anode chamber, and electronic grade pure water is loaded into the cathode chamber to continuously perform five times of electrolysis. The electrolysis voltage is adjusted to 10-35 V, the primary purified perfluorohexyl sulfonic acid is added dropwise into the cathode chamber until the electrolysis current is 0.5-3 A, the temperature of each chamber is increased to 40-70 °C, and the electrolysis is performed for 1-1.5 h. After the single electrolysis is completed, the solution in the cathode chamber is taken out, electronic grade pure water is added for washing until the content of metal ions in the washing water is less than 1 ppb, and then electronic grade pure water is supplemented for the next electrolysis until the electrolysis is completed;

[0023] (6) after 5 times of continuous electrolysis, the electrolysis solution in the anode chamber is taken and the metal ions therein are tested; then 0.05 μm, 0.02 μm, 0.01 μm and 0.01 μm filter cores are connected in series, and first washed with electronic-grade pure water for 24 h, and then the particle number in the water is tested; when the particle number of 0.3 μm in the water is less than 10 ea / ml, the particle number of 0.2 μm is less than 50 ea / ml, and the particle number of 0.1 μm is less than 100 ea / ml, the electrolysis solution is filtered for 24-48 h, and thus electronic-grade perfluorohexyl sulfonic acid is obtained.

[0024] As a further preferred technical scheme of the present application, the step (4) and the step (5) further comprise a resin electrolysis purification operation.

[0025] The electronic-grade sulfuric acid of E1 level is diluted with electronic-grade pure water to a mass fraction of 3-5%, and then placed in the anode chamber, and then the hydrogen-type cation resin treated in the step (3) is added, and the cathode chamber is filled with electronic-grade pure water to continuously electrolyze for five times, the electrolysis voltage is adjusted to 30-55 V, and the diluted electronic-grade sulfuric acid is added dropwise to the cathode chamber until the electrolysis current is 0.8-3.2 A, and the temperature of each chamber is raised to 40-70 °C for electrolysis for 0.7-1 h; after each electrolysis, the solution in the cathode chamber is taken out, electronic-grade pure water is added for washing until the metal ions in the washing water are less than 1 ppb, and then electronic-grade pure water is added for the next electrolysis until the electrolysis is completed; after the electrolysis is completed, the electronic-grade sulfuric acid in the anode chamber is separated from the resin, and then the resin is washed with electronic-grade pure water until the pH of the washing solution is 6-7;

[0026] The step (5) adds the washed resin to the anode chamber.

[0027] Further, in the resin electrolysis purification operation, the volume ratio of the hydrogen-type cation resin to the diluted electronic-grade sulfuric acid is 1:2-1:5;

[0028] In the first electrolysis, the electrolysis voltage is 30-35 V, the electrolysis current is 0.8-1.2 A, the temperature of each chamber is raised to 40-70 °C, and electrolysis is performed for 0.7-1 h;

[0029] In the second electrolysis, the electrolysis voltage is 35-40 V, the electrolysis current is 1.3-1.7 A, the temperature of each chamber is raised to 40-70 °C, and electrolysis is performed for 0.7-1 h;

[0030] In the third electrolysis, the electrolysis voltage is 40-45 V, the electrolysis current is 1.8-2.2 A, the temperature of each chamber is raised to 40-70 °C, and electrolysis is performed for 0.7-1 h;

[0031] In the fourth electrolysis, the electrolysis voltage is 45-50 V, the electrolysis current is 2.3-2.7 A, the temperature of each chamber is raised to 40-70 °C, and electrolysis is performed for 0.7-1 h;

[0032] In the fifth electrolysis, the electrolysis voltage is 50-55V, and the electrolysis current is 2.8-3.2A; the temperature of each electrolysis chamber is raised to 40-70℃, and electrolysis is performed for 0.7-1h.

[0033] Further, in step (5), the volume ratio of the anode chamber resin after washing to the primary purified perfluorohexyl sulfonic acid is 1:1-1:3.

[0034] Further, in step (3), the ion exchange column is three columns connected in series, and the resin in the ion exchange column is hydrogen type cation resin.

[0035] Further, in the first electrolysis of step (5), the electrolysis voltage is 10-15V, and the electrolysis current is 0.5-1A; the temperature of each electrolysis chamber is raised to 40-70℃, and electrolysis is performed for 1-1.5h.

[0036] In the second electrolysis, the electrolysis voltage is 15-20V, and the electrolysis current is 1-1.5A; the temperature of each electrolysis chamber is raised to 40-70℃, and electrolysis is performed for 1-1.5h.

[0037] In the third electrolysis, the electrolysis voltage is 20-25V, and the electrolysis current is 1.5-2A; the temperature of each electrolysis chamber is raised to 40-70℃, and electrolysis is performed for 1-1.5h.

[0038] In the fourth electrolysis, the electrolysis voltage is 25-30V, and the electrolysis current is 2-2.5A; the temperature of each electrolysis chamber is raised to 40-70℃, and electrolysis is performed for 1-1.5h.

[0039] In the fifth electrolysis, the electrolysis voltage is 30-35V, and the electrolysis current is 2.5-3A; the temperature of each electrolysis chamber is raised to 40-70℃, and electrolysis is performed for 1-1.5h.

[0040] The electronic grade perfluorohexyl sulfonic acid prepared by the above method can be used as an acid regulator for the preparation of a top anti-reflective film of a photoresist.

[0041] Compared with the prior art, the present application has the following advantages:

[0042] (1) The present application is simple to operate, and electronic grade perfluorohexyl sulfonic acid is prepared by resin impurity removal and electrolysis impurity removal, and electrolysis impurity removal is operated under low voltage and low current conditions, which is low in energy consumption, low in cost, and high in safety factor.

[0043] (2) As mentioned above, the perfluorohexyl sulfonic acid treated in the present application is an organic acid with carbon-fluorine bond in the skeleton structure, which is difficult to treat and has high complexity. In addition, due to the long skeleton structure, the viscosity of the aqueous solution thereof is very high, and after the water in the high-concentration perfluorohexyl sulfonic acid is distilled apart, only a colloidal perfluorohexyl sulfonic acid is obtained, and the impurities cannot be separated and are enriched in the perfluorohexyl sulfonic acid. The ion exchange method, freezing method, rectification method, salt transfer purification method, and high polymer adsorbent adsorption method cannot make the content of single impurity metal ion in the perfluorohexyl sulfonic acid reach the E4 level of the minimum standard. The present application ingeniously uses the high-purity special resin primary purification and electrolytic fine purification combined treatment, so that the index of the purified perfluorohexyl sulfonic acid can reach the minimum E4 standard.

[0044] (3) In order to avoid the problems that the impurity ions move slowly at low temperature, the electrolysis effect is poor, and the electrode plate electrolysis rate is accelerated at high temperature and high acidity, so that trace metal ions in the product are electrolyzed, the product is increased, the product in the electrolytic tank is kept at a constant and moderate temperature, the impurity ions can be kept at a faster moving speed, and the more impurity metal ions in the electrode plate do not enter the product after multiple electrolysis, and the problems of serious foaming in the electrode chamber at high temperature, easy to cause the tank to burst, and the reaction occurs after the foam contacts the electrode clamp, which causes the perfluorohexyl sulfonic acid in the electrode chamber to turn green, and the treatment difficulty is increased again.

[0045] (4) The present application uses expensive high-purity platinum gold electrode plate as anode and relatively cheap high-purity graphite as cathode plate, which reduces the production cost on the basis of ensuring the purity of the product.

[0046] (5) In the electrolytic impurity removal process, when high-purity platinum-gold plates with a purity of 99.99% are used as anode plates, sodium ions and calcium ions in the anode plates will continuously enter the product under high-temperature and electrolytic force in an acidic condition. Since the movement effect of sodium ions is better and the movement effect of calcium ions is general, the content of single impurity metal ions in the obtained product is between 1-10 ppb, which meets the standard of E4 in GB / T41881-2022, but can only reach the minimum use standard of the customer, and the product has low added value. Moreover, the content of sodium ions and calcium ions in the obtained product is close to 10 ppb, and slight deviation will lead to unqualified product and high rework rate. Therefore, in order to facilitate stable control, reduce the rework rate and improve the product added value, so that the product quality can reach the E3 level, the application further electrolytically purifies the primary purified resin, and when performing electrolytic impurity removal of perfluorohexyl sulfonic acid, the primary purified resin is placed in the anode chamber to adsorb calcium ions, sodium ions and other metal impurity ions with high content. After the electrolysis is completed, the content of calcium ions, sodium ions and other metal ions in the product can be controlled to be below 1 ppb, which meets the standard of E3 in GB / T41881-2022, and further improves the added value of the product on the basis of meeting the use standard of the customer. DETAILED DESCRIPTION

[0047] The preparation method of the electronic-grade perfluorohexyl sulfonic acid will be described in detail below in combination with specific examples.

[0048] In the following examples, all operations were performed in a hundred-level clean room. The content of single metal ions in the electronic-grade pure water was less than 1 ppb. The electrolytic cell and each component including the electrolytic cell anode chamber, the anode plate, the cathode chamber, the cathode plate and the intermediate separation membrane. In the electrolytic cell, the anode plate is a high-purity platinum-gold plate, and the cathode plate is a high-purity graphite plate.

[0049] In step (2), the electronic-grade hydrofluoric acid was purchased from Dohlee Chemical Co., Ltd. After dilution, the content of single metal ions in the electronic-grade hydrofluoric acid was less than 1 ppb.

[0050] In step (1), the perfluorohexyl sulfonic acid was purchased from Shanghai Jizisheng Chemical Co., Ltd., and the total element analysis results are shown in Table 1.

[0051] Table 1 Total element analysis results of commercially available perfluorohexyl sulfonic acid (unit: ppb)

[0052] Al Ba Ca Cd Co Cr Cu Fe K Mg Mn Na Zn Ni 319 56 3493 0 0 211 607 734 1500 348 6.3 1659 0 12

[0053] The total element analysis results of the primary purified perfluorohexyl sulfonic acid are shown in Table 2.

[0054] Table 2 Total element analysis results of the primary purified perfluorohexyl sulfonic acid (unit: ppb)

[0055] Al Ba Ca Cd Co Cr Cu Fe K Mg Mn Na Zn Ni 4 3 9 1 2 1 2 3 6 5 3 198 3 1

[0056] Example 1

[0057] A method for preparing electronic-grade perfluorohexyl sulfonic acid, comprising the following steps:

[0058] (1) dilute perfluorohexyl sulfonic acid with electronic-grade pure water to a mass fraction of 2%;

[0059] (2) dilute electronic-grade hydrofluoric acid with electronic-grade pure water to a mass fraction of 5%;

[0060] (3) take 10 L of hydrogen-type cation resin and load it into three ion exchange columns connected in series, use 30 L of the diluted electronic-grade hydrofluoric acid from step (2) to perform countercurrent washing for 24 h, and then use electronic-grade pure water to perform cocurrent washing until the pH of the washing water is 7;

[0061] (4) use the ion exchange resin treated in step (3) to continuously purify the diluted perfluorohexyl sulfonic acid from step (1) twice to obtain primary purified perfluorohexyl sulfonic acid, wherein the metal ions and their contents are shown in Table 2;

[0062] (5) use electronic-grade pure water to wash the electrolytic cell and each component (anode chamber, anode plate, cathode chamber, cathode plate, and intermediate separator membrane) of the electrolytic cell until the content of all metal ions in the washing water is less than 1 ppb;

[0063] Take 1000 ml of the primary purified perfluorohexyl sulfonic acid from step (4) and place it in the anode chamber, and place 100 ml of electronic-grade pure water in the cathode chamber to perform a first electrolysis, adjust the electrolysis voltage to 10 V, add the primary purified perfluorohexyl sulfonic acid to the cathode chamber dropwise until the electrolysis current is 0.5 A, raise the temperature of each chamber to 65°C, and electrolyze for 1 h; after the first electrolysis is completed, take out all the solution in the cathode chamber, and wash it with electronic-grade pure water until the content of metal ions in the washing water is less than 1 ppb;

[0064] Perform a second electrolysis by supplementing the cathode chamber with electronic-grade pure water, adjust the electrolysis voltage to 15 V, add the primary purified perfluorohexyl sulfonic acid to the cathode chamber dropwise until the electrolysis current is 1 A, raise the temperature of each chamber to 65°C, and electrolyze for 1 h; after the second electrolysis is completed, take out all the solution in the cathode chamber, and wash it with electronic-grade pure water until the content of metal ions in the washing water is less than 1 ppb;

[0065] Perform a third electrolysis by supplementing the cathode chamber with electronic-grade pure water, adjust the electrolysis voltage to 20 V, add the primary purified perfluorohexyl sulfonic acid to the cathode chamber dropwise until the electrolysis current is 1.5 A, raise the temperature of each chamber to 65°C, and electrolyze for 1 h; after the third electrolysis is completed, take out all the solution in the cathode chamber, and wash it with electronic-grade pure water until the content of metal ions in the washing water is less than 1 ppb;

[0066] The cathode chamber was supplemented with electronic grade pure water for four times of electrolysis, the electrolysis voltage was adjusted to 25 V, primary purified perfluorohexylsulfonic acid was added dropwise to the cathode chamber until the electrolysis current was 2 A, the temperature of each chamber was raised to 65°C, and electrolysis was performed for 1 h; after four times of electrolysis, the solution in the cathode chamber was taken out and washed with electronic grade pure water until the metal ions in the washing water were less than 1 ppb;

[0067] The cathode chamber was supplemented with electronic grade pure water for five times of electrolysis, the electrolysis voltage was adjusted to 30 V, primary purified perfluorohexylsulfonic acid was added dropwise to the cathode chamber until the electrolysis current was 2.5 A, the temperature of each chamber was raised to 65°C, and electrolysis was performed for 1 h;

[0068] (6) After five times of continuous electrolysis, the electrolyzed solution in the anode chamber was taken out and sampled for testing of metal ions; then filter cartridges with pore sizes of 0.05 μm, 0.02 μm, 0.01 μm and 0.01 μm were connected in series, electronic grade pure water was used for dynamic circulation washing for 24 h, then the particle number in the water was tested, the 0.3 μm particle number was 9 ea / ml, the 0.2 μm particle number was 37 ea / ml, and the 0.1 μm particle number was 88 ea / ml, the electrolyzed solution was dynamically circulated and filtered for 24 h, thereby electronic grade perfluorohexylsulfonic acid was obtained.

[0069] The results of full element analysis of the electronic grade perfluorohexylsulfonic acid are shown in Table 3, the content of single metal ion is less than 10 ppb, and the electronic grade perfluorohexylsulfonic acid can be used as an acid regulator in top anti-reflective film of photoresist.

[0070] Al Ba Ca Cd Co Cr Cu Fe K Mg Mn Na Zn Ni Product 2 2 9 1 2 1 2 1 4 2 1 8 2 1

[0071] Table 3: Results of full element analysis of electronic grade perfluorohexylsulfonic acid in Example 1 (unit: ppb)

[0072] Examples 2-10 are the same as other steps of Example 1, only the mass fraction of perfluorohexylsulfonic acid after dilution in step (1) is changed, and the results of single metal ion content in the final electronic grade perfluorohexylsulfonic acid product are shown in Table 4.

[0073] Table 4: Single metal ion content in electronic grade perfluorohexylsulfonic acid product in Examples 2-10

[0074]

[0075] From the above examples, when the mass fraction of perfluorohexylsulfonic acid after dilution in step (1) is 1.5-3%, the single metal ion content in the obtained perfluorohexylsulfonic acid can reach E4 level, and the effect is better. Therefore, the mass fraction of perfluorohexylsulfonic acid after dilution is preferably 1.5%-3%.

[0076] Examples 11-20

[0077] Examples 11-20 are the same as other steps of Example 1, only changing the mass fraction of electronic grade hydrofluoric acid after dilution in step (2), the results of the content of single metal ions in the final electronic grade perfluorohexylsulfonic acid product are shown in Table 5.

[0078] Table 5 Content of single metal ions in electronic grade perfluorohexylsulfonic acid product in Examples 11-20

[0079]

[0080] From the above examples, when the mass fraction of electronic grade hydrofluoric acid after dilution in step (2) is 3-6%, the content of single metal ions in the obtained electronic grade perfluorohexylsulfonic acid can reach E4 level, which is better. Considering the use of the least amount of hydrofluoric acid to reduce cost, therefore, the mass fraction of electronic grade hydrofluoric acid after dilution is preferably 3%.

[0081] Examples 21-27

[0082] Examples 21-27 are the same as other steps of Example 1, only changing the number of electrolysis in step (5). When the number of electrolysis is other values, the results of total element analysis of electronic grade perfluorohexylsulfonic acid product are shown in Table 6.

[0083] Table 6 Results of total element analysis of electronic grade perfluorohexylsulfonic acid product in Examples 21-27

[0084]

[0085]

[0086] From the above examples, when the number of electrolysis is greater than or equal to 5-6 times, the content of metal ions in the final product can reach E4 level, and the number of electrolysis is preferably 5 times.

[0087] Examples 28-42

[0088] Examples 28-42 are the same as other steps of Example 1, only changing the electrolysis temperature in step (5). When the electrolysis temperature is other values, the results of the content of single metal ions in the final electronic grade perfluorohexylsulfonic acid product are shown in Table 7.

[0089] Table 7 Content of single metal ions in electronic grade perfluorohexylsulfonic acid product in Examples 28-42

[0090]

[0091]

[0092] From the above examples, when the electrolysis temperature in step (5) is 40-70°C, the total metal ion content in the perfluorohexyl sulfonic acid obtained can reach E4 level, and the effect is better. In view of reducing energy consumption and reducing cost, therefore, the electrolysis temperature is preferably 40°C.

[0093] Examples 43-46

[0094] Examples 43-46 are the same as other steps of Example 1, only the electrolysis voltage in step (5) is changed. When the electrolysis voltage is other values, the single metal ion content in the final electronic grade perfluorohexyl sulfonic acid product is shown in Table 8.

[0095] Table 8 Single metal ion content in electronic grade perfluorohexyl sulfonic acid product in Examples 43-46

[0096]

[0097] From the above examples, when 10V≤1st electrolysis voltage≤15V, 15V≤2nd electrolysis voltage≤20V, 20V≤3rd electrolysis voltage≤25V, 25V≤4th electrolysis voltage≤30V, 30V≤5th electrolysis voltage≤35V in step (5), the metal ion content in the electronic grade perfluorohexyl sulfonic acid obtained can reach E4 level, and the effect is better. In view of reducing energy consumption and reducing cost, therefore, the 1st electrolysis voltage is preferably 10V, the 2nd electrolysis voltage is preferably 15V, the 3rd electrolysis voltage is preferably 20V, the 4th electrolysis voltage is preferably 25V, and the 5th electrolysis voltage is preferably 30V.

[0098] Examples 47-58

[0099] Examples 47-58 are the same as other steps of Example 1, only the electrolysis current in step (5) is changed. When the electrolysis current is other values, the single metal ion content in the final electronic grade perfluorohexyl sulfonic acid product is shown in Table 9.

[0100] Table 9 Single metal ion content in electronic grade perfluorohexyl sulfonic acid product in Examples 47-58

[0101]

[0102] From the above examples, when 0.5A≤1st electrolysis current≤1A, 1A≤2nd electrolysis current≤1.5A, 1.5A≤3rd electrolysis current≤2A, 2A≤4th electrolysis current≤2.5A, 2.5A≤5th electrolysis current≤3A in step (5), the total metal ion content in the perfluorohexyl sulfonic acid obtained can reach E4 level, and the effect is better. In view of reducing energy consumption and reducing cost, therefore, the 1st electrolysis current is preferably 0.5A, the 2nd electrolysis current is preferably 1A, the 3rd electrolysis current is preferably 1.5A, the 4th electrolysis current is preferably 2A, and the 5th electrolysis current is preferably 2.5A.

[0103] Examples 59-78

[0104] Examples 59-78 are the same as other steps of Example 1, only the electrolysis time in step (5) is changed. When the electrolysis time is other values, the single metal ion content results in the final electronic grade perfluorohexylsulfonic acid product are shown in Table 10.

[0105] Table 10 Single metal ion content in electronic grade perfluorohexylsulfonic acid product in Examples 59-78

[0106]

[0107] From the above examples, when 1 h≤1st electrolysis time≤1.5 h, 1 h≤2nd electrolysis time≤1.5 h, 1 h≤3rd electrolysis time≤1.5 h, 1 h≤4th electrolysis time≤1.5 h, 1 h≤5th electrolysis time≤1.5 h in step (5), the total metal ion in the perfluorohexylsulfonic acid obtained can reach E4 standard, and the effect is better. Considering reducing energy consumption and cost, therefore, the 1st electrolysis time is 1 h, the 2nd electrolysis time is 1 h, the 3rd electrolysis time is 1 h, the 4th electrolysis time is 1 h, and the 5th electrolysis time is 1 h are preferred.

[0108] Examples 79-85

[0109] Examples 79-85 are the same as other steps of Example 1, only resin electrolysis purification operation is added in step (4) and step (5), and electrolysis purification washed resin is added in the anode chamber in step (5). When the volume ratio of hydrogen type resin and diluted electronic grade sulfuric acid is changed only during resin electrolysis purification, and the volume ratio of hydrogen type resin and diluted electronic grade sulfuric acid is other values, whether the metal ion content in the final electronic grade perfluorohexylsulfonic acid product reaches E3 level is shown in Table 11.

[0110] Table 11 Single metal ion content in electronic grade perfluorohexylsulfonic acid in Examples 79-85

[0111]

[0112] From the above examples, when the volume ratio of hydrogen type resin and diluted electronic grade sulfuric acid is 1:2-1:8, the metal ion content of the final product can reach E3 level. The volume ratio of hydrogen type resin and diluted electronic grade sulfuric acid is 1:2-1:5 is preferred.

[0113] Examples 86-93

[0114] Examples 86-93 are the same as other steps of Example 1, only adding resin electrolytic purification operation in step (4) and step (5), and adding resin after electrolytic purification washing in step (5) anode chamber. When resin electrolytic purification, only change the number of hydrogen type resin electrolytic purification. When the number of hydrogen type resin electrolytic purification is other value, whether the metal ion content of the final electronic grade perfluorohexyl sulfonic acid product reaches E3 level is shown in Table 12.

[0115] Table 12 Single metal ion content in electronic grade perfluorohexyl sulfonic acid in Examples 86-93

[0116]

[0117] From the above examples, when the number of continuous electrolysis of hydrogen type resin is 5-7 times, the metal ion content of the final product can reach E3 level, and the continuous electrolysis of 5 times is preferred.

[0118] Examples 94-100 Examples

[0119] Examples 94-100 are the same as other steps of Example 1, only changing the volume ratio of hydrogen type resin and perfluorohexyl sulfonic acid after electrolytic purification washing in step (5) anode chamber. When the volume ratio of hydrogen type resin and perfluorohexyl sulfonic acid after electrolytic purification washing is other value, whether the metal ion content of the final electronic grade perfluorohexyl sulfonic acid product reaches E3 level is shown in Table 13.

[0120] Table 13 Single metal ion content in electronic grade perfluorohexyl sulfonic acid in Examples 94-100

[0121]

[0122] From the above examples, when the volume ratio of hydrogen type resin and perfluorohexyl sulfonic acid after purification washing in anode chamber is 1:1-1:3, the metal ion content of the final product can reach E3 level.

[0123] Examples 101-109 Examples

[0124] Examples 101-109 are the same as other steps of Example 1, only adding resin electrolytic purification operation in step (4) and step (5), and adding resin after electrolytic purification washing in step (5) anode chamber. When resin electrolytic purification, only change the voltage value in the resin electrolytic purification operation. When the voltage value is other value, whether the metal ion content of the final electronic grade perfluorohexyl sulfonic acid product reaches E3 level is shown in Table 14.

[0125] Table 14 Single metal ion content in electronic grade perfluorohexyl sulfonic acid in Examples 101-109

[0126]

[0127] From the above examples, when the resin electrolysis purification, 30V≤1st electrolysis voltage≤35V, 35V≤2nd electrolysis voltage≤40V, 40V≤3rd electrolysis voltage≤45V, 45V≤4th electrolysis voltage≤50V, 50≤5th electrolysis voltage≤55V, the metal ion content of the electronic grade perfluorohexyl sulfonic acid obtained reaches E3 level, and the effect is better. In view of reducing energy consumption and reducing cost, the 1st electrolysis voltage is preferably selected as 30V, the 2nd electrolysis voltage is preferably selected as 35V, the 3rd electrolysis voltage is preferably selected as 40V, the 4th electrolysis voltage is preferably selected as 45V, and the 5th electrolysis voltage is preferably selected as 50V.

[0128] Examples 110-125

[0129] Examples 110-125 are the same as other steps of Example 1, only the resin electrolysis purification operation is added in step (4) and step (5), and the resin after electrolysis purification washing is added to the anode chamber. When the resin electrolysis purification, only the current value in the resin electrolysis purification operation is changed. When the current value is other value, whether the metal ion content in the final electronic grade perfluorohexyl sulfonic acid product reaches E3 level is shown in Table 15.

[0130] Table 15 Single metal ion content in electronic grade perfluorohexyl sulfonic acid in Examples 110-125

[0131]

[0132] From the above examples, when the resin electrolysis purification, 30V≤1st electrolysis voltage≤35V, 35V≤2nd electrolysis voltage≤40V, 40V≤3rd electrolysis voltage≤45V, 45V≤4th electrolysis voltage≤50V, 50≤5th electrolysis voltage≤55V, the metal ion content of the electronic grade perfluorohexyl sulfonic acid obtained reaches E3 level, and the effect is better. In view of reducing energy consumption and reducing cost, the 1st electrolysis voltage is preferably selected as 30V, the 2nd electrolysis voltage is preferably selected as 35V, the 3rd electrolysis voltage is preferably selected as 40V, the 4th electrolysis voltage is preferably selected as 45V, and the 5th electrolysis voltage is preferably selected as 50V.

[0133] Examples 126-138

[0134] Examples 126-138 are the same as other steps of Example 1, only the resin electrolysis purification operation is added, and the resin after electrolysis purification washing is added to the anode chamber to participate in the electrolysis reaction. When the resin electrolysis purification, only the electrolysis time in the resin electrolysis purification operation is changed. When the electrolysis time is other value, whether the metal ion content in the final electronic grade perfluorohexyl sulfonic acid product reaches E3 level is shown in Table 16.

[0135] Table 16 Single metal ion content in electronic grade perfluorohexanesulfonic acid in Examples 126-138

[0136]

[0137] From the above examples, when the resin electrolysis purification, 0.7h≤1 electrolysis time≤1h, 0.7h≤2 electrolysis time≤1h, 0.7h≤3 electrolysis time≤1h, 0.7h≤4 electrolysis time≤1h, 0.7h≤5 electrolysis time≤1h, the total metal ion content in the perfluorohexanesulfonic acid obtained reaches E3 level, the effect is better. Considering the reduction of energy consumption, reduce the cost, therefore, the preferred choice of 1 electrolysis time is 0.7h, 2 electrolysis time is 0.7h, 3 electrolysis time is 0.7A, 4 electrolysis time is 0.7h, 5 electrolysis time is 0.7h.

[0138] Examples 139-154

[0139] Examples 139-154 are the same as other steps of Example 1, only in step (4) and step (5) increase the resin electrolysis purification operation, and in step (5) anode chamber is added after electrolysis purification of the resin. When the resin electrolysis purification, only change the electrolysis temperature in the resin electrolysis purification operation. When the electrolysis temperature is other value, whether the metal ion content in the final electronic grade perfluorohexanesulfonic acid product reaches E3 level, see Table 17.

[0140] Table 17 Single metal ion content in electronic grade perfluorohexanesulfonic acid in Examples 139-154

[0141]

[0142] From the above examples, when the resin electrolysis purification electrolysis temperature is 40-70℃, the total metal ion content in the perfluorohexanesulfonic acid obtained reaches E3 standard, the effect is better. Considering the reduction of energy consumption, reduce the cost, therefore, the preferred choice of electrolysis temperature is 40℃.

[0143] From the above examples, when the resin electrolysis purification operation is added between the step (4) and the step (5), and the electrolysis is carried out by adding the washed electrolysis purification resin in the anode chamber of step (5), the grade of the perfluorohexanesulfonic acid obtained can be further improved, the product grade is improved from E4 to E3 level, and the added value of the product is further improved.

Claims

1. A process for the preparation of electronic grade perfluorohexanesulfonic acid, characterized in that, Comprising the following steps: (1) perfluorohexanesulfonic acid is diluted with electronic grade pure water to a mass fraction of 1.5-3%; (2) electronic grade hydrofluoric acid is diluted with electronic grade pure water to a mass fraction of 3-6%; (3) hydrogen cation resin is loaded into an ion exchange column, and then the diluted electronic grade hydrofluoric acid in step (2) is used for countercurrent washing, followed by electronic grade pure water for cocurrent washing until the pH of the washing water is 6-7; (4) the primary purified perfluorohexanesulfonic acid obtained by purifying the diluted perfluorohexanesulfonic acid in step (1) with the ion exchange resin treated in step (3), wherein the metal ions and their contents are as follows: unit: ppb; (5) first, resin electrolysis purification operation is carried out: Take electronic grade sulfuric acid of E1 level, dilute it with electronic grade pure water to a mass fraction of 3-5%, and place it in the anode chamber, then add the hydrogen cation resin treated in step (3), the volume ratio of the hydrogen cation resin to the diluted electronic grade sulfuric acid is 1:2-1:5; the cathode chamber is loaded with electronic grade pure water for continuous electrolysis for five times: In the first electrolysis, the electrolysis voltage is 30-35V, the electrolysis current is 0.8-1.2A; the temperature of each electrode chamber is raised to 40-70℃, and electrolysis is carried out for 0.7-1h; In the second electrolysis, the electrolysis voltage is 35-40V, the electrolysis current is 1.3-1.7A; the temperature of each electrode chamber is raised to 40-70℃, and electrolysis is carried out for 0.7h-1h; In the third electrolysis, the electrolysis voltage is 40-45V, the electrolysis current is 1.8-2.2A; the temperature of each electrode chamber is raised to 40-70℃, and electrolysis is carried out for 0.7h-1h; In the fourth electrolysis, the electrolysis voltage is 45-50V, the electrolysis current is 2.3-2.7A; the temperature of each electrode chamber is raised to 40-70℃, and electrolysis is carried out for 0.7h-1h; In the fifth electrolysis, the electrolysis voltage is 50-55V, the electrolysis current is 2.8-3.2A; the temperature of each electrode chamber is raised to 40-70℃, and electrolysis is carried out for 0.7h-1h; After each single electrolysis, the solution in the cathode chamber is taken out, electronic grade pure water is added for washing until the metal ions in the washing water are less than 1ppb, then electronic grade pure water is added for the next electrolysis until the electrolysis is completed; after the electrolysis is completed, the electronic grade sulfuric acid in the anode chamber is separated from the resin, then the resin is washed with electronic grade pure water until the pH of the washing solution is 6-7; Then, electronic grade pure water is used to wash the electrolytic cell and each component until the content of all metal ions in the washing water is less than 1ppb; The primary purified perfluorohexanesulfonic acid in step (4) is placed in the anode chamber, the washed resin is added to the anode chamber, and electronic grade pure water is loaded into the cathode chamber for continuous electrolysis for five times, the electrolysis voltage is adjusted to 10-35V, the primary purified perfluorohexanesulfonic acid is added dropwise to the cathode chamber until the electrolysis current is 0.5-3A, the temperature of each electrode chamber is raised to 40-70℃, and electrolysis is carried out for 1-1.5h; after each single electrolysis, the solution in the cathode chamber is taken out, electronic grade pure water is added for washing until the metal ions in the washing water are less than 1ppb, then electronic grade pure water is added for the next electrolysis until the electrolysis is completed; (6) After the continuous electrolysis is ended for 5 times, the electrolysis solution in the anode chamber is taken, and metal ions in the electrolysis solution are sampled and tested; then, filter cores with 0.05 μm, 0.02 μm, 0.01 μm and 0.01 μm are connected in series, electronic-grade pure water is used to dynamically circulate and wash for 24 h, and then the particle number in the water is tested, when the particle number of 0.3 μm in the water is less than 10 ea / ml, the particle number of 0.2 μm in the water is less than 50 ea / ml, and the particle number of 0.1 μm in the water is less than 100 ea / ml, the electrolysis solution is dynamically circulated and filtered for 24-48 h, and then electronic-grade perfluorohexyl sulfonic acid is obtained.

2. A process for the preparation of electronic grade perfluorohexanesulfonic acid as claimed in claim 1, wherein, In step (5), the volume ratio of the resin to the primary purified perfluorohexyl sulfonic acid after washing of the anode chamber is 1:1-1:

3.

3. A process for the preparation of electronic grade perfluorohexanesulfonic acid as claimed in claim 2, wherein, In step (3), the ion exchange column is 3 columns connected in series.

4. A process for the preparation of electronic grade perfluorohexanesulfonic acid as claimed in claim 3, wherein, In step (5), when the primary purified perfluorohexyl sulfonic acid in step (4) is put into the anode chamber, the washed resin is added into the anode chamber, and electronic-grade pure water is filled into the cathode chamber to continuously electrolyze for five times, in the first electrolysis, the electrolysis voltage is 10-15 V, the electrolysis current is 0.5-1 A; the temperature of each chamber is increased to 40-70 ℃, and electrolysis is performed for 1-1.5 h.

5. A process for the preparation of electronic grade perfluorohexanesulfonic acid as claimed in claim 4, wherein, In step (5), when the primary purified perfluorohexyl sulfonic acid in step (4) is put into the anode chamber, the washed resin is added into the anode chamber, and electronic-grade pure water is filled into the cathode chamber to continuously electrolyze for five times, in the second electrolysis, the electrolysis voltage is 15-20 V, the electrolysis current is 1-1.5 A; the temperature of each chamber is increased to 40-70 ℃, and electrolysis is performed for 1-1.5 h.

6. A process for the preparation of electronic grade perfluorohexanesulfonic acid as claimed in claim 5, wherein, In step (5), when the primary purified perfluorohexyl sulfonic acid in step (4) is put into the anode chamber, the washed resin is added into the anode chamber, and electronic-grade pure water is filled into the cathode chamber to continuously electrolyze for five times, in the third electrolysis, the electrolysis voltage is 20-25 V, the electrolysis current is 1.5-2 A; the temperature of each chamber is increased to 40-70 ℃, and electrolysis is performed for 1-1.5 h.

7. A process for the preparation of electronic grade perfluorohexanesulfonic acid as claimed in claim 6, wherein, In step (5), when the primary purified perfluorohexyl sulfonic acid in step (4) is put into the anode chamber, the washed resin is added into the anode chamber, and electronic-grade pure water is filled into the cathode chamber to continuously electrolyze for five times, in the fourth electrolysis, the electrolysis voltage is 25-30 V, the electrolysis current is 2-2.5 A; the temperature of each chamber is increased to 40-70 ℃, and electrolysis is performed for 1-1.5 h.

8. A process for the preparation of electronic grade perfluorohexanesulfonic acid as claimed in claim 7, wherein, In step (5), when the primary purified perfluorohexyl sulfonic acid in step (4) is put into the anode chamber, the washed resin is added into the anode chamber, and electronic-grade pure water is filled into the cathode chamber to continuously electrolyze for five times, in the fifth electrolysis, the electrolysis voltage is 30-35 V, the electrolysis current is 2.5-3 A; the temperature of each chamber is increased to 40-70 ℃, and electrolysis is performed for 1-1.5 h.

Images