Method for purifying electronic-grade semiconductor stripping solution

Abstract

A kind of electronic grade semiconductor stripping liquid purification method, comprising: providing electronic grade semiconductor stripping liquid residual liquid, and carry out pH detection, when pH<7, drop NaOH solution to stop;The residual liquid after neutralization is extracted into distillation kettle, and the aqueous solution of residual liquid is removed, and the water is collected into storage tank from the top of kettle, and the bottom of kettle is waste liquid containing salt, and salt is removed by cooling, crystallization, centrifugation, and the aqueous solution of electronic grade semiconductor stripping liquid is recovered by redistillation;Water is extracted into dehydration kettle, and water is separated, and the bottom of kettle is electronic grade semiconductor stripping liquid crude product;The crude product is refined using rectifying kettle, and electronic grade semiconductor stripping liquid pure product is collected from the top of kettle;Electronic grade semiconductor stripping liquid pure product is microfiltrated using peristaltic pump, and electronic grade semiconductor stripping liquid fine product is prepared.The present application not only effectively improves the utilization rate of stripping liquid, reduces environmental pollution, provides convenient conditions for waste treatment, but also improves safety factor, reduces operating cost, and is worth popularizing and using in industry.

Description

Technical Field

[0001] This invention relates to the field of distillation and purification technology for residual electronic-grade semiconductor stripping fluid, and particularly to a method for purifying electronic-grade semiconductor stripping fluid. Background Technology

[0002] Electronic-grade ultrapure semiconductor stripping fluid is an indispensable solvent in chip manufacturing, and it has extremely high requirements for the content of electronic-grade semiconductor stripping fluid and metal ions. However, the quality of electronic-grade semiconductor stripping fluid used in chip cleaning agents, photoresists, etc., often does not meet the requirements, and the residual liquid cannot be recycled. Moreover, the residual liquid is difficult to treat and is environmentally unfriendly.

[0003] To meet the quality requirements of electronic-grade ultrapure semiconductor stripping fluid, chip manufacturers need to continuously improve conventional production processes, while phasing out outdated processes and avoiding the use of substandard electronic-grade semiconductor stripping fluid. Only through technological innovation and the elimination of substandard electronic-grade semiconductor stripping fluid can chip manufacturers reduce production costs and achieve environmentally friendly development.

[0004] The search for a purification method for electronic-grade semiconductor stripping fluid that allows for recycling of residual electronic-grade semiconductor stripping fluid, effectively reduces production costs, solves the environmental management problem of residual electronic-grade semiconductor stripping fluid, and provides strong support for enterprise development has become one of the technical problems that urgently need to be solved by those skilled in the art.

[0005] Therefore, in view of the problems existing in the prior art, the designer of this invention, based on years of experience in this industry, actively researched and improved the technology, and thus came up with the present invention: a method for purifying electronic-grade semiconductor stripping fluid. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies, such as the non-compliance of quality of electronic-grade semiconductor stripping solutions used in chip cleaning agents, photoresists, etc., the inability to recycle residual liquids, the difficulty in treating residual liquids, and the environmental unfriendliness of the environment, by providing a purification method for electronic-grade semiconductor stripping solutions.

[0007] To achieve the objective of this invention, this invention provides a method for purifying electronic-grade semiconductor stripping fluid, the method comprising:

[0008] Step S1: Provide residual electronic-grade semiconductor stripping solution and test its pH value. When pH < 7, add the residual electronic-grade semiconductor stripping solution to the reactor, start stirring, and add NaOH solution dropwise to the reactor until... Stop adding NaOH solution when the time is right;

[0009] Step S2: The residual electronic-grade semiconductor stripping liquid after neutralization with NaOH solution is pumped into the distillation column bottom. Under reduced pressure, the aqueous solution containing the residual electronic-grade semiconductor stripping liquid is removed and collected from the top of the distillation column bottom into a storage tank. The bottom of the distillation column bottom is a waste liquid containing salt. The salt in the waste liquid is further removed by cooling, crystallization, and centrifugation. The mother liquor is redistilled to recover the aqueous solution containing the residual electronic-grade semiconductor stripping liquid.

[0010] Step S3: The aqueous solution containing residual electronic-grade semiconductor stripping fluid collected from the storage tank is pumped into the dehydration tower bottom under reduced pressure. The electronic-grade semiconductor stripping fluid and water are separated by dehydration. Water is separated from the top of the dehydration tower bottom. If the electronic-grade semiconductor stripping fluid content in the water separated from the top of the dehydration tower bottom is less than or equal to 2%, it is considered qualified. The bottom of the dehydration tower bottom contains crude electronic-grade semiconductor stripping fluid with a content greater than 85%.

[0011] Step S4: The crude electronic-grade semiconductor stripping fluid with a content greater than 85% is purified under reduced pressure using a distillation column reboiler, and the pure electronic-grade semiconductor stripping fluid with a content greater than 99.5% is collected from the top of the distillation column reboiler.

[0012] Step S5: Using an ICP-MS inductively coupled plasma mass spectrometer, the metal ion content in the pure electronic-grade semiconductor stripping solution with a purity greater than 99.5% is detected, and the material is filtered through a peristaltic pump to obtain a high-quality electronic-grade semiconductor stripping solution with a purity greater than 99.9%.

[0013] Optionally, the concentration of the NaOH solution used in step S1 is 20% to 25%, and the purity of the solid NaOH used to prepare the NaOH solution is greater than 99%.

[0014] Optionally, the reaction vessel and associated pipeline used for acid-base neutralization are lined with polytetrafluoroethylene.

[0015] Optionally, the stirring time during the acid-base neutralization process is 30 minutes.

[0016] Optionally, the distillation column kettle is made of stainless steel SUS304, and the supporting pipelines and storage tanks are polished and passivated.

[0017] Optionally, under the reduced pressure conditions, the vacuum degree is 0.092 MPa, the bottom temperature of the distillation column is 134–136°C, and the top temperature of the distillation column is 109–111°C.

[0018] Optionally, the dehydration tower and its associated condenser, pipelines and storage tanks are all made of stainless steel SUS304 and are polished and passivated.

[0019] Optionally, under the reduced pressure conditions, the vacuum degree is 0.096 MPa, the internal temperature of the dehydration tower is 118–120°C, and the top temperature of the dehydration tower is 45–48°C.

[0020] Optionally, the distillation column reboiler and its associated condenser, pipelines and storage tanks are all made of stainless steel SUS304 and are polished and passivated.

[0021] Optionally, under the reduced pressure conditions, the vacuum degree is 0.098 MPa, the internal temperature of the distillation column bottom is 125–130°C, and the temperature at the top of the distillation column bottom is 105–108°C.

[0022] Optionally, the pure electronic-grade semiconductor stripping fluid with a content greater than 99.5% is filtered through a peristaltic pump using a micro-membrane filter at a flow rate of 8–10 BV and a pore size of 0.1 nm.

[0023] Optionally, a high-quality electronic-grade semiconductor stripping solution with a content greater than 99.9% is prepared, wherein the metal ion content of the high-quality electronic-grade semiconductor stripping solution is less than 10 ppb.

[0024] In summary, the electronic-grade semiconductor stripping fluid purification method of this invention fully utilizes distillation to purify the residual electronic-grade semiconductor stripping fluid. This not only effectively improves the utilization rate of the electronic-grade semiconductor stripping fluid and reduces environmental pollution, providing convenient conditions for waste treatment, but also improves the safety factor because the purification method is a physical method with relatively low temperature and pressure. At the same time, the use of a DCS system for operation greatly reduces operating costs. The described electronic-grade semiconductor stripping fluid purification method is worthy of promotion and use in the industry. Attached Figure Description

[0025] Figure 1 The diagram shows the purification method of the electronic-grade semiconductor stripping solution of the present invention.

[0026] Figure 2 The diagram shown is a block diagram of the purification method for electronic-grade semiconductor stripping solution of the present invention. Detailed Implementation

[0027] To explain in detail the technical content, structural features, objectives, and effects of this invention, the following will provide a detailed description in conjunction with embodiments and accompanying drawings.

[0028] Please see Figure 1 , Figure 2 , Figure 1 The diagram shows the purification method of the electronic-grade semiconductor stripping solution of the present invention. Figure 2 The diagram shown is a block diagram of the purification method for electronic-grade semiconductor stripping solution of the present invention. The purification method for electronic-grade semiconductor stripping solution includes:

[0029] Step S1: Provide residual electronic-grade semiconductor stripping solution and test its pH value. When pH < 7, add the residual electronic-grade semiconductor stripping solution to the reactor, start stirring, and add NaOH solution dropwise to the reactor until... Stop adding NaOH solution when the time is right;

[0030] Step S2: The residual electronic-grade semiconductor stripping liquid after neutralization with NaOH solution is pumped into the distillation column bottom. Under reduced pressure, the aqueous solution containing the residual electronic-grade semiconductor stripping liquid is removed and collected from the top of the distillation column bottom into a storage tank. The bottom of the distillation column bottom is a waste liquid containing salt. The salt in the waste liquid is further removed by cooling, crystallization, and centrifugation. The mother liquor is redistilled to recover the aqueous solution containing the residual electronic-grade semiconductor stripping liquid.

[0031] Step S3: The aqueous solution containing residual electronic-grade semiconductor stripping fluid collected from the storage tank is pumped into the dehydration tower bottom under reduced pressure. The electronic-grade semiconductor stripping fluid and water are separated by dehydration. Water is separated from the top of the dehydration tower bottom. If the electronic-grade semiconductor stripping fluid content in the water separated from the top of the dehydration tower bottom is less than or equal to 2%, it is considered qualified. The bottom of the dehydration tower bottom contains crude electronic-grade semiconductor stripping fluid with a content greater than 85%.

[0032] Step S4: The crude electronic-grade semiconductor stripping fluid with a content greater than 85% is purified under reduced pressure using a distillation column reboiler, and the pure electronic-grade semiconductor stripping fluid with a content greater than 99.5% is collected from the top of the distillation column reboiler.

[0033] Step S5: Using an ICP-MS inductively coupled plasma mass spectrometer, the metal ion content in the pure electronic-grade semiconductor stripping solution with a purity greater than 99.5% is detected, and the material is filtered through a peristaltic pump to obtain a high-quality electronic-grade semiconductor stripping solution with a purity greater than 99.9%.

[0034] In this invention, by way of non-limiting example, the concentration of the NaOH solution used in step S1 is 20%–25%, and the purity of the solid NaOH used to prepare the NaOH solution is greater than 99%. Using high-purity solid NaOH to prepare the NaOH solution is to reduce impurities and ensure the quality of the finished product. Simultaneously, the reaction vessel and its associated pipelines used for acid-base neutralization are lined with polytetrafluoroethylene (PTFE) to prevent the introduction of metal ions. Preferably, the stirring time during the acid-base neutralization process is 30 minutes.

[0035] In step S2, the distillation column reboiler is made of SUS304 stainless steel, and the supporting pipelines and storage tanks are polished and passivated. Under the reduced pressure conditions, the vacuum degree is 0.092 MPa, the bottom temperature of the distillation column reboiler is 134–136°C, and the top temperature of the distillation column reboiler is 109–111°C.

[0036] In step S3, the dehydration tower kettle and its associated condenser, pipelines, and storage tanks are all made of SUS304 stainless steel and undergo polishing and passivation treatment. Under the reduced pressure conditions, the vacuum degree is 0.096 MPa, the internal temperature of the dehydration tower kettle is 118–120°C, the top temperature of the dehydration tower kettle is 45–48°C, and the content of electronic-grade semiconductor stripping fluid in the water separated from the top of the dehydration tower kettle is less than or equal to 2% to be considered qualified, while the bottom of the dehydration tower kettle contains crude electronic-grade semiconductor stripping fluid with a content greater than 85%.

[0037] In step S4, the distillation column reboiler and its associated condenser, pipelines, and storage tanks are all made of SUS304 stainless steel and undergo polishing and passivation treatment. Under the reduced pressure conditions, the vacuum degree is 0.098 MPa, the internal temperature of the distillation column reboiler is 125–130°C, the top temperature of the distillation column reboiler is 105–108°C, and the top of the distillation column reboiler yields a pure electronic-grade semiconductor stripping solution with a purity greater than 99.5%.

[0038] In step S5, the pure electronic-grade semiconductor stripping fluid with a content greater than 99.5% is filtered through a peristaltic pump using a micro-membrane filter at a flow rate of 8-10 BV. The pore size of the micro-membrane is 0.1 nm to ensure that metal ions cannot pass through, thereby obtaining a refined electronic-grade semiconductor stripping fluid with a content greater than 99.9%, wherein the metal ion content of the refined electronic-grade semiconductor stripping fluid is below 10 ppb.

[0039] To more intuitively reveal the technical solution of the present invention and highlight its beneficial effects, the purification method and principle of the electronic-grade semiconductor stripping solution are now described in conjunction with specific embodiments. In the specific embodiments, the process parameters and sequence of steps used in the purification method of the electronic-grade semiconductor stripping solution are merely examples and should not be considered as limitations on the technical solution of the present invention.

[0040] Step S1: Neutralize the sample in batches using a pipette. Detect the pH value using pH test paper or a pH meter. If the pH is <7, neutralization is required. Prepare a 20%–25% NaOH solution using deionized water with solid NaOH (purity >99%). Then, pump the solution into a NaOH solution dropper. Add the liquid alkali dropwise to neutralize the residual electronic-grade semiconductor stripping solution. Until then, the dropping temperature is 30–50℃;

[0041] Step S2: The neutralized residual electronic-grade semiconductor stripping solution is pumped into the distillation column reboiler under reduced pressure, with the pumped volume being [missing information - likely a percentage of the distillation volume]. Salt removal is carried out under reduced pressure. When the vacuum degree is 0.092MPa, the bottom temperature of the vessel is 135℃ and the top temperature of the tower is 110℃. The aqueous solution containing electronic-grade semiconductor stripping fluid is removed, and the solution in the vessel contains salt. The salt is transferred to the crystallization vessel. After cooling, crystallization, and centrifugation, the salt is sent to the solid waste treatment plant. The mother liquor is redistilled to recover the aqueous solution containing the residual electronic-grade semiconductor stripping fluid.

[0042] Step S3: The extracted electronic-grade semiconductor stripping solution is pumped into the dehydration tower reactor at a rate equal to [percentage]% of the reactor's volume. Dehydration is carried out under reduced pressure. When the vacuum degree is 0.096MPa, the bottom temperature is 118-120℃ and the top temperature is 45-48℃. The content of electronic-grade semiconductor stripping liquid in the top dewatering water is less than or equal to 2%, which is considered qualified. The content of electronic-grade semiconductor stripping liquid in the bottom crude product is more than 85%.

[0043] Step S4: The electronic-grade semiconductor stripping solution with a content of 85% or higher is then pumped back into the distillation column reboiler, the pumping volume being [percentage missing] of the reboiler's volume. Distillation is carried out under reduced pressure. When the vacuum degree is 0.098 MPa, the bottom temperature is 125-130℃, and the top temperature is 105-108℃, an electronic-grade semiconductor stripping solution with a purity of over 99.5% is obtained.

[0044] Step S5: To increase the content of electronic-grade semiconductor stripping fluid and reduce the content of metal ions, a peristaltic pump is used to filter the fluid through a 0.1-nanometer micromembrane at a flow rate of 8-10 BV. The content of metal ions and main components is detected by ICP-MS inductively coupled plasma mass spectrometry and gas chromatography. Finally, a high-quality electronic-grade semiconductor stripping fluid with a content of over 99.9% and a metal ion content of less than 10 ppb is obtained.

[0045] As will be readily apparent to those skilled in the art, the purification method for electronic-grade semiconductor stripping fluid of the present invention has the following advantages over traditional production processes: (1) It fully utilizes distillation to purify the residual electronic-grade semiconductor stripping fluid, effectively improving the utilization rate of the electronic-grade semiconductor stripping fluid; (2) It reduces environmental pollution and provides convenient conditions for waste disposal; (3) Since the purification method is a physical method, the temperature and pressure are relatively low, thus improving the safety factor; (4) It adopts DCS system operation, which greatly reduces operating costs.

[0046] In summary, the electronic-grade semiconductor stripping fluid purification method of this invention fully utilizes distillation to purify the residual electronic-grade semiconductor stripping fluid. This not only effectively improves the utilization rate of the electronic-grade semiconductor stripping fluid and reduces environmental pollution, providing convenient conditions for waste treatment, but also improves the safety factor because the purification method is a physical method with relatively low temperature and pressure. At the same time, the use of a DCS system for operation greatly reduces operating costs. The described electronic-grade semiconductor stripping fluid purification method is worthy of promotion and use in the industry.

[0047] Those skilled in the art will understand that various modifications and variations can be made to this invention without departing from its spirit or scope. Therefore, if any modification or variation falls within the scope of the appended claims and their equivalents, the invention is considered to cover such modifications and variations.

Claims

1. A method for purifying electronic-grade semiconductor stripping solution, characterized in that, The purification method for the electronic-grade semiconductor stripping solution includes: Step S1: Provide residual electronic-grade semiconductor stripping solution and test its pH value. When pH < 7, add the residual electronic-grade semiconductor stripping solution to the reactor, start stirring, and add NaOH solution dropwise to the reactor until... Stop adding NaOH solution when the time is right; Step S2: The residual electronic-grade semiconductor stripping liquid after neutralization with NaOH solution is pumped into the distillation column bottom. Under reduced pressure, the aqueous solution containing the residual electronic-grade semiconductor stripping liquid is removed and collected from the top of the distillation column bottom into a storage tank. The bottom of the distillation column bottom is a waste liquid containing salt. The salt in the waste liquid is further removed by cooling, crystallization, and centrifugation. The mother liquor is redistilled to recover the aqueous solution containing the residual electronic-grade semiconductor stripping liquid. Step S3: The aqueous solution containing residual electronic-grade semiconductor stripping fluid collected from the storage tank is pumped into the dehydration tower bottom under reduced pressure. The electronic-grade semiconductor stripping fluid and water are separated by dehydration. Water is separated from the top of the dehydration tower bottom. If the electronic-grade semiconductor stripping fluid content in the water separated from the top of the dehydration tower bottom is less than or equal to 2%, it is considered qualified. The bottom of the dehydration tower bottom contains crude electronic-grade semiconductor stripping fluid with a content greater than 85%. Step S4: The crude electronic-grade semiconductor stripping fluid with a content greater than 85% is purified under reduced pressure using a distillation column reboiler, and the pure electronic-grade semiconductor stripping fluid with a content greater than 99.5% is collected from the top of the distillation column reboiler. Step S5: Using an ICP-MS inductively coupled plasma mass spectrometer, the metal ion content in the pure electronic-grade semiconductor stripping solution with a purity greater than 99.5% is detected, and the material is filtered through a peristaltic pump to obtain a high-quality electronic-grade semiconductor stripping solution with a purity greater than 99.9%.

2. The purification method for electronic-grade semiconductor stripping solution as described in claim 1, characterized in that, The concentration of the NaOH solution used in step S1 is 20% to 25%, and the purity of the solid NaOH used to prepare the NaOH solution is greater than 99%.

3. The purification method for electronic-grade semiconductor stripping solution as described in claim 1, characterized in that, The reactor and its associated pipelines used for acid-base neutralization are lined with polytetrafluoroethylene.

4. The purification method for electronic-grade semiconductor stripping solution as described in claim 1, characterized in that, The stirring time during the acid-base neutralization process is 30 minutes.

5. The purification method for electronic-grade semiconductor stripping solution as described in claim 1, characterized in that, The distillation column kettle is made of SUS304 stainless steel, and the supporting pipelines and storage tanks are all polished and passivated.

6. The purification method for electronic-grade semiconductor stripping solution as described in claim 5, characterized in that, The vacuum degree under the reduced pressure conditions is 0.092 MPa, the bottom temperature of the distillation column is 134–136 °C, and the top temperature of the distillation column is 109–111 °C.

7. The purification method for electronic-grade semiconductor stripping solution as described in claim 1, characterized in that, The dehydration tower, along with its associated condenser, pipelines, and storage tanks, are all made of SUS304 stainless steel and have undergone polishing and passivation treatment.

8. The purification method for electronic-grade semiconductor stripping solution as described in claim 7, characterized in that, The vacuum degree under the decompression conditions is 0.096 MPa, the internal temperature of the dehydration tower is 118–120°C, and the top temperature of the dehydration tower is 45–48°C.

9. The purification method for electronic-grade semiconductor stripping solution as described in claim 1, characterized in that, The distillation column reboiler and its associated condenser, pipelines, and storage tanks are all made of SUS304 stainless steel and have undergone polishing and passivation treatment.

10. The purification method for electronic-grade semiconductor stripping solution as described in claim 9, characterized in that, The vacuum degree under the reduced pressure conditions is 0.098 MPa, the internal temperature of the distillation column bottom is 125–130°C, and the temperature at the top of the distillation column bottom is 105–108°C.

11. The purification method for electronic-grade semiconductor stripping solution as described in claim 1, characterized in that, Electronic-grade semiconductor stripping fluid with a purity greater than 99.5% is filtered through a peristaltic pump using a micro-membrane filter at a flow rate of 8–10 BV and a pore size of 0.1 nm.

12. The purification method for electronic-grade semiconductor stripping solution as described in claim 1, characterized in that, A high-quality electronic-grade semiconductor stripping solution with a purity greater than 99.9% was obtained, wherein the metal ion content of the high-quality electronic-grade semiconductor stripping solution was less than 10 ppb.

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