Comprehensive recycling process for wafer cutting, grinding and polishing wastewater in semiconductor process

Abstract

The application provides a wafer cutting-grinding-polishing wastewater resource utilization comprehensive recovery process in a semiconductor process, under the condition of not adding any chemical reagent, sequentially performing solid-liquid separation treatment through a dynamic ceramic membrane filtration system and a cluster filter, and after the produced clear liquid is detected to be qualified, purifying the clear liquid through an UF system and / or an RO system to realize semiconductor process wastewater recovery and utilization, and simultaneously providing a preparation method of a ceramic membrane used in the process, since the ceramic membrane contains titanium oxide and has hydrophilic properties, contains zirconium oxide and has high bending hardness, a high wear coefficient, a surface coating modification resistant to pollution and not easy to block, and high filtration precision. The process directly performs solid-liquid separation, simultaneously recovers solid and liquid phases, recovers semiconductor fine particles, does not contain other impurities and chemical reagent residues, directly in-situ concentrates air pressure dewatering and drying in the cluster filter, and packs, is beneficial to recovery and utilization and convenient to transport, the wastewater recovery rate is higher than 97%, and the semiconductor fine particle recovery rate is higher than 98%.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology in the wafer material processing of the semiconductor industry, and particularly to a comprehensive recycling process for wastewater from wafer cutting, grinding and polishing in semiconductor manufacturing. Background Technology

[0002] In the semiconductor manufacturing industry, high-purity water is the basic water used in the cutting, grinding, and polishing processes of wafers or chips, and the entire process consumes a large amount of high-purity water. During subtractive processing such as cutting, grinding, and polishing, some semiconductor materials (mainly wafers or chips) are removed, and these materials are mostly distributed in the high-purity water in the form of fine particles. Because this type of water contains relatively few other impurities, both the high-purity water and the fine semiconductor material powder are high-value resource products. To maintain and realize their value, a resource-based treatment process without using any chemical reagents is needed to separate and reuse them.

[0003] Currently, wastewater from the cutting, grinding, and polishing processes of semiconductor wafers / wafers contains a large amount of fine semiconductor material powder. These materials, including Si, Ce, CdTe, and GaAsP, vary in particle size from nanometer to sub-nanometer to micrometer due to different processes and manufacturing methods. Nanometer and sub-micrometer-sized particulate semiconductor material powders, due to their high surface energy, form a stable solid-liquid mixture with water, maintaining a stable state over a long period without settling or agglomerating. Common methods involve using chemical agents to destabilize, agglomerate, flocculate, and separate the solid and liquid phases. However, this method cannot recover both the clean water and the fine semiconductor material powder through resource recovery. For example, Chinese patent CN201910648428.X discloses a method for treating semiconductor grinding wastewater, which uses the addition of chemical reagents (flocculators, coagulants) for sedimentation treatment. For example, Chinese patent CN201910730408.7 discloses a method for treating semiconductor wastewater. This method also involves adding chemical reagents to first coagulate suspended solids, and then using a filtration and separation device to separate the solids and liquids, thereby treating the wastewater. However, these methods consume large amounts of chemical reagents, making further processing impossible. The resulting semiconductor material powder and water cannot be reused, leading to secondary pollution.

[0004] In addition, some people use filters to treat these wastewaters directly. Although this allows for multi-stage filtration and prevents secondary pollution, the process is too long, the filtration precision is insufficient, the processing capacity is limited, and it is difficult to collect fine semiconductor material powder. For example, Chinese patent CN201621421971.4 discloses a device for recycling grinding and cutting wastewater in the semiconductor industry, which uses multiple sets of equipment for multiple filtration processes. The entire treatment device has an excessively long process line, unstable processing capacity, and the system is difficult to operate stably and continuously.

[0005] For the selection of filtration equipment, hollow fiber membranes or tubular ceramic membranes are commonly used filter elements. Although hollow fiber membranes and tubular ceramic membranes have high filtration accuracy, the filter elements themselves are static during operation. In actual engineering applications, it has been found that wastewater containing fine semiconductor material powder, colloidal particles, and angular particulate matter causes a sharp drop in static membrane flux, severe membrane fouling or damage, and membrane clogging. Frequent cleaning is required, consuming large amounts of chemicals. The cleaning wastewater becomes regeneration wastewater, resulting in low water recovery rates and the inability to recover fine semiconductor material powder.

[0006] Therefore, improving the filter element is key to solving such problems. For example, Chinese patent CN201811170407.3 discloses a batch complete filtration process for API solution in the pre-crystallization process of pharmaceutical production. It mentions using a rotating ceramic membrane to filter fine particles. Compared with a static tube ceramic membrane, it performs better in terms of less clogging and maintaining stable flux. However, for wastewater containing fine semiconductor material powder with high hardness and angular particulate matter, it is easy to cause the membrane surface to be worn and damaged, the filtration accuracy to fail, and the filtration cannot be normal. Ultrafine powder and colloids with a particle size distribution of 5nm to 60nm contaminate the membrane surface, clog the membrane pores, and cause a sharp drop in flux. The treatment system cannot operate continuously and stably, and the recovery rate of clean water and fine semiconductor material powder is not high.

[0007] In view of this, it is necessary to improve the existing wastewater treatment methods generated in semiconductor manufacturing processes in order to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to disclose a comprehensive recycling process for wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing. This process does not use any chemical agents, maintains the cleanliness of semiconductor material microparticles, uses a dynamic ceramic membrane filtration system to achieve nanoscale high-precision solid-liquid separation, and uses a cluster filter for in-situ dehydration and drying, thereby centrally recovering semiconductor material microparticles and water resources.

[0009] To achieve the above objectives, this invention provides a comprehensive recycling process for wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing, comprising the following steps:

[0010] Step (1): The wastewater from wafer cutting, grinding and polishing in the semiconductor process is treated by solid-liquid separation through a dynamic ceramic membrane filtration system. The resulting clear liquid is tested and qualified before entering the clear water tank for further treatment. If it is not qualified, solid-liquid separation is performed again and the resulting concentrated liquid enters the concentrated liquid tank.

[0011] Step (2): The concentrate from step (1) is passed into a cluster filter for secondary solid-liquid separation. Fine particles are deposited on the surface of the filter element of the cluster filter to form a filter cake layer, while the permeate is returned to the dynamic ceramic membrane filtration system for recirculation.

[0012] Step (3): After multiple cycles of processing, all the concentrated liquid generated by the dynamic ceramic membrane filtration system is discharged into the bundled filter for final solid-liquid separation. The filter cake layer is dehydrated and dried in situ until the moisture content of the filter cake layer is less than 30%. Automatic slag discharge is then performed to recover the fine particles.

[0013] Step (4): The water from the clear water tank in step (1) is purified by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water for later use. The concentrated water generated by the reverse osmosis system is recycled to the dynamic ceramic membrane filtration system for further processing, and finally solid-liquid separation is achieved.

[0014] The filter element of the dynamic ceramic membrane filtration system is a ceramic membrane. The separation layer of the ceramic membrane has hydrophilic properties due to the presence of titanium oxide and high bending hardness due to the presence of zirconium oxide.

[0015] The filter element surface of the cluster filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the cluster filter and reduce the moisture content of the filter cake layer.

[0016] In some embodiments, the clear liquid generated by the dynamic ceramic membrane filtration system in step (1) is introduced into a clear water tank for further treatment when the turbidity is detected to be less than 0.3 NTU.

[0017] In some embodiments, the fine particles are composed of any one of Si, Ce, SiC, CdTe, GaAs, InP, CdS, GaAlAs, and GaAsP.

[0018] In some embodiments, the operating pressure of the dynamic ceramic membrane filtration system is 0.01–0.2 MPa, the filtration accuracy of the ceramic membrane is 5–200 nm, and its rotation speed is 50–500 Hz.

[0019] In some embodiments, the working pressure of the cluster filter is 0.2 to 1 MPa, and the filtration accuracy of the filter element of the cluster filter is 0.2 to 1 μm.

[0020] In some embodiments, the wastewater in step (1) is first subjected to ultrasonic pretreatment and then filtered and separated by a dynamic ceramic membrane filtration system.

[0021] In some embodiments, the frequency of the ultrasonic treatment is 20–60 kHz and the intensity is 2.0–10.0 kW.

[0022] In some embodiments, ultrasonic pretreatment is performed when the median particle size D (50) of the fine particles in the wastewater is less than 50 nm.

[0023] To achieve the above objectives, the present invention also provides a comprehensive recycling process for wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing processes, comprising the following steps:

[0024] Step (1): The wastewater from wafer cutting, grinding and polishing in the semiconductor process is treated by solid-liquid separation through a primary cluster filter. Fine particles are deposited on the surface of the filter element of the primary cluster filter to form a filter cake layer. The permeate enters the dynamic ceramic membrane filtration system for treatment.

[0025] Step (2): The clear liquid produced after being processed by the dynamic ceramic membrane filtration system is tested and qualified before entering the clear water tank for further processing. If it fails to meet the requirements, it will enter the primary cluster filter for further processing. The resulting concentrated liquid will be returned to the primary cluster filter for further processing.

[0026] Step (3): After multiple cycles of processing, all the concentrated liquid generated by the dynamic ceramic membrane filtration system is discharged into the first-stage bundled filter for final solid-liquid separation. The filter cake layer is then dehydrated and dried in situ until the moisture content of the filter cake layer is less than 30%. Automatic slag discharge is then performed to recover the fine particles.

[0027] Step (4): The water from the clear water tank in step (2) is purified by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water for later use. The concentrated water generated by the reverse osmosis system is returned to the primary cluster filter for circulation treatment, and finally solid-liquid separation is achieved.

[0028] The filter element of the dynamic ceramic membrane filtration system is a ceramic membrane. The separation layer of the ceramic membrane has hydrophilic properties due to the presence of titanium oxide and high bending hardness due to the presence of zirconium oxide.

[0029] The filter element surface of the primary cluster filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the primary cluster filter and reduce the moisture content of the filter cake layer.

[0030] In some embodiments, the concentrated liquid outlet of the primary cluster filter is also connected to a secondary cluster filter, and the processing capacity of the primary cluster filter is higher than that of the secondary cluster filter; in step (3), the concentrated liquid of the primary cluster filter enters the secondary cluster filter for in-situ dehydration and drying treatment until the moisture content of the filter cake layer is less than 30%, and automatic slag discharge is performed to recover the fine particles.

[0031] In some embodiments, when the particle size of the fine particles in the wastewater is less than 1 μm, process of claim 1 is used; when the particle size of the fine particles in the wastewater is not less than 1 μm, process of claim 9 is used.

[0032] The second objective of this invention is to disclose a method for preparing a ceramic membrane. The ceramic membrane prepared by this method, as a filter element of a dynamic ceramic membrane filtration system, has high precision, high membrane surface hardness, low surface roughness, longer membrane life and better anti-fouling performance, and can be applied to the treatment of high-hardness, ultra-wear-resistant, and ultra-fine semiconductor wastewater.

[0033] To achieve the above objectives, this invention provides a method for preparing a ceramic film for the comprehensive recycling of wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing processes, comprising the following steps:

[0034] Step (1): Prepare the support layer

[0035] Micron-sized alumina powder, sintering aid, pore-forming agent, dispersant, and binder are mixed in proportion and ball-milled for 4-6 hours to form a slurry. The slurry is then produced by spray granulation and dry pressing to form a support layer preform. After drying to remove moisture, it is then fired.

[0036] Step (2): Prepare the intermediate layer

[0037] Micron-sized alumina powder, sintering aid, grinding aid, dispersant, and binder are mixed in proportion and ball-milled for 6-8 hours to prepare an intermediate layer film slurry. After coating, drying, and firing, an intermediate layer of film is formed.

[0038] The ceramic film prepared in this step has an intermediate layer pore size of 0.2–2 μm, a roughness Ra of 2.5–10 μm, and a Mohs hardness HM of 3–4.

[0039] Step (3): Preparation of the separation layer

[0040] Nano-alumina powder, sintering aid, binder, and zirconium oxide sol are mixed evenly in a certain proportion to form a separation layer slurry, which is then coated, dried, and fired to form a membrane separation layer.

[0041] The separation layer of the ceramic membrane prepared in this step has a pore size of 50–80 nm, a roughness Ra of 0.2–0.4 μm, and a Mohs hardness HM of 8–9.

[0042] In some embodiments, the median particle size D (50) of the alumina powder in step (1) is 5 to 30 μm, the median particle size D (50) of the alumina powder in step (2) is 5 to 10 μm, and the median particle size D (50) of the alumina powder in step (3) is 0.1 to 1 μm.

[0043] In some embodiments, the sintering aid in step (1) is titanium dioxide (0.5-1.25 wt%), silicon dioxide (2-5 wt%), or magnesium oxide (0.5-2.5 wt%), the pore-forming agent is one or more of starch (3-8 wt%), carbon powder (1-7 wt%), and cellulose (1.5-5 wt%), the dispersant is one or two of sodium hexametaphosphate and PEG (2-4 wt%), and the binder is a polyvinyl alcohol solution with a concentration of 10-15% (2-5 wt%).

[0044] In some embodiments, the sintering aid in step (2) is silicon dioxide (5-10 wt%), the grinding aid is sodium hexametaphosphate (0.5-1.5 wt%), the dispersant is PEG (1-2 wt%), and the binder is a prepared PVA solution with a concentration of 2-5% (0.2-0.8 wt%).

[0045] In some embodiments, the sintering aid in step (3) is titanium dioxide (10-15 wt%), the binder is a PVA solution with a concentration of 5-10% (2-5 wt%), and zirconium oxide sol (2-10 wt%).

[0046] In some embodiments, the ceramic membrane is the filter element of the aforementioned dynamic ceramic membrane filtration system.

[0047] Compared with the prior art, the beneficial effects of the present invention are: (1) No chemical reagents are added, no pH adjustment is made by reagents, solid and liquid are directly separated, and both solid and liquid phases are recovered at the same time; (2) The recovered water has low turbidity and does not contain other impurities and chemical reagent residues. It can be directly used as the feed water of the UF system and / or RO system for purification treatment. The recovered semiconductor microparticles do not contain other impurities and chemical reagent residues. They do not use energy-consuming processes such as evaporation and drying. They are directly dehydrated and dried by air pressure and bagged, which is conducive to recycling and convenient transportation. The wastewater recovery rate is higher than 97%, and the semiconductor microparticle recovery rate is higher than 98%; (3) The ceramic membrane has hydrophilic properties due to the presence of titanium oxide and high bending hardness and wear resistance due to the presence of zirconium oxide. The surface coating is modified to resist pollution and is not easy to clog. It has high precision and high mechanical strength. Attached Figure Description

[0048] Figure 1 The diagrams show the integrated recycling process for wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing, as illustrated in Examples 1-2.

[0049] Figure 2 This is a diagram illustrating the comprehensive recycling process for wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing, as shown in Example 3.

[0050] Figure 3 This is a SEM image of the support layer of the ceramic membrane shown in this invention;

[0051] Figure 4 This is a SEM image of the separation layer of the ceramic membrane shown in this invention;

[0052] Figure 5 This is a pore size distribution diagram of the ceramic membrane shown in this invention;

[0053] Figure 6 This is a curve comparing the flux attenuation of the ceramic membrane shown in this invention with that of existing ceramic membranes;

[0054] Figure 7 This is a comparison diagram of pure water and wastewater after treatment by the process shown in this invention;

[0055] Figure 8 Image of semiconductor microparticles after processing by the process shown in this invention;

[0056] Figure 9 This is a distribution diagram of the engineering flux monitoring of the dynamic ceramic membrane filtration system shown in this invention. Detailed Implementation

[0057] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the scope of protection of the present invention. Example

[0058] like Figure 1 , Figure 3-9 As shown, a comprehensive recycling process for wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing includes the following steps:

[0059] Step (1): The wastewater from wafer cutting, grinding and polishing in the semiconductor process is treated by solid-liquid separation through a dynamic ceramic membrane filtration system. The resulting clear liquid is tested and qualified before entering the clear water tank for further treatment. If it is not qualified, solid-liquid separation is performed again and the resulting concentrated liquid enters the concentrated liquid tank.

[0060] Step (2): The concentrate from step (1) is passed into a cluster filter for secondary solid-liquid separation. Fine particles are deposited on the surface of the filter element of the cluster filter to form a filter cake layer, while the permeate is returned to the dynamic ceramic membrane filtration system for recirculation.

[0061] Step (3): After multiple cycles of processing, all the concentrated liquid generated by the dynamic ceramic membrane filtration system is discharged into the bundled filter for final solid-liquid separation. The filter cake layer is dehydrated and dried in situ until the moisture content of the filter cake layer is less than 30%. Automatic slag discharge is then performed to recover the fine particles.

[0062] Step (4): The water from the clear water tank in step (1) is purified by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water for later use. The concentrated water generated by the reverse osmosis system is recycled to the dynamic ceramic membrane filtration system for further processing, and finally solid-liquid separation is achieved.

[0063] The filter element of the dynamic ceramic membrane filtration system is a ceramic membrane. The separation layer of the ceramic membrane has hydrophilic properties due to the presence of titanium oxide and high bending hardness due to the presence of zirconium oxide.

[0064] The filter element surface of the cluster filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the cluster filter and reduce the moisture content of the filter cake layer.

[0065] In this embodiment, the clarified liquid generated by the dynamic ceramic membrane filtration system is tested by an online intelligent testing instrument (including but not limited to a turbidity meter and a conductivity meter) and, if it meets the water quality standards, enters the clear water tank to be used as the feed water for the UF system and / or OR system. If it does not meet the standards, it is returned to the dynamic ceramic membrane filtration system. Only when the clarified liquid generated by the dynamic ceramic membrane filtration system in step (1) is tested and found to have a turbidity of less than 0.3 NTU is it allowed to enter the clear water tank for downstream purification treatment.

[0066] The fine particles described in this invention are composed of any one of Si, Ce, SiC, CdTe, GaAs, InP, CdS, GaAlAs, and GaAsP, but are not limited to this. Any fine particles generated during the subtractive processing of semiconductor materials can be treated using this process. It should be clarified that the wastewater from the semiconductor process contains fine particles of any one and only one of the above-mentioned components. While it is possible to recycle fine particles containing multiple components, further classification and recycling are not possible. Therefore, the treatment process disclosed in this embodiment is mainly applied to wastewater containing a single component.

[0067] When using this process to treat wastewater from semiconductor manufacturing, the wastewater generated during the cutting, grinding, and polishing processes can first be collected in a collection tank to achieve homogenization, buffering, and stabilization. The operating pressure of the dynamic ceramic membrane filtration system is 0.01–0.2 MPa, the filtration accuracy of the ceramic membrane is 5–200 nm, and its rotation speed is 50–500 Hz. The operating pressure of the cluster filter is 0.2–1 MPa, and the filtration accuracy of the filter element in the cluster filter is 0.2–1 μm. In practical applications, different process parameters are selected and adjusted according to the particulate matter content of the wastewater in the semiconductor manufacturing process to achieve the best treatment effect. However, the operating parameters of both the dynamic ceramic membrane filtration system and the cluster filter are selected within the above-mentioned value ranges. The backwashing process of the dynamic ceramic membrane filtration system can be appropriately selected.

[0068] like Figure 6 , Figure 9 As shown, the ceramic membrane of this invention has a higher flux and more stable performance compared to ordinary ceramic membranes in the prior art (such as the ceramic membrane disclosed in Chinese Patent CN201811170407.3), and its flux decay is slower over 10 days of operation under the same conditions. In this embodiment, a single dynamic ceramic membrane filtration system is configured with 5 ceramic membranes. Figure 6 The flux figures shown are from tests conducted on a single dynamic ceramic membrane filtration system. For example... Figure 9 As shown, when multiple dynamic ceramic membrane filtration systems are used simultaneously, operating at full load for one day, the flux decline is minimal. This demonstrates that the ceramic membrane prepared in this invention and the configured dynamic ceramic membrane filtration system exhibit more stable and reliable performance, higher throughput, and longer service life.

[0069] Because the ceramic membrane in this invention has strong hydrophilicity and high bending hardness, it exhibits stronger dirt resistance, higher mechanical strength, and higher and more stable flux. The concentrated liquid after solid-liquid separation in the dynamic ceramic membrane filtration system enters a cluster filter for secondary solid-liquid separation. Since the filter element surface of the cluster filter is coated with a nanofiber membrane, the pore size and porosity of which are higher than the filter medium inside the filter element allow fine particles to quickly deposit on the nanofiber membrane surface, forming a filter cake layer, while water rapidly permeates. By controlling the controller of the cluster filter, the filter cake layer can be purged in situ with gas and / or washed with clean water. After washing and drying, the filter cake layer is then expanded by backflushing and / or vibration, causing cracks in the filter cake layer and achieving automatic slag discharge.

[0070] The wastewater recovery rate after treatment by this process is higher than 97%, and the semiconductor fine particle recovery rate is higher than 98%. Example

[0071] When performing solid-liquid separation on wastewater generated in semiconductor manufacturing processes (including cutting, grinding, and polishing processes), pretreatment can be performed first, and then the wastewater can be processed according to the processing technology in Example 1.

[0072] The wastewater in step (1) is first subjected to ultrasonic pretreatment and then filtered and separated by a dynamic ceramic membrane filtration system. The frequency of the ultrasonic treatment is 20-60 kHz and the intensity is 2.0-10.0 kW.

[0073] Ultrasonic pretreatment of wastewater utilizes the cavitation effect generated when ultrasound propagates in a medium, causing the rapid growth and collapse of tiny bubbles in the solution, generating strong local disturbances, disrupting the stable state of the solid-liquid dispersed phase of the wastewater, promoting the aggregation of fine particles, and facilitating their entry into the dynamic ceramic membrane filtration system. This forms a dynamic cross-flow filtration on the ceramic membrane surface, resulting in higher solid-liquid separation efficiency. At the same time, these fine particles are less likely to deposit on the ceramic membrane surface.

[0074] The above pretreatment steps can be selectively applied based on the size of the fine particles in the wastewater. When the median particle size D(50) of the fine particles in the wastewater is less than 50 nm, ultrasonic pretreatment is performed. It should be noted that when the fine particles D(50) in the wastewater are less than 50 nm, ultrasonic pretreatment can effectively break the stable system, and the pre-destabilized wastewater improves the solid-liquid separation performance of the subsequent dynamic ceramic membrane filtration system. When the fine particles D(50) in the wastewater are greater than 100 nm, the pretreatment has no significant impact on the solid-liquid separation performance of the subsequent dynamic ceramic membrane filtration system, and ultrasonic pretreatment is not required; the wastewater can directly enter the dynamic ceramic membrane filtration system for treatment. Example

[0075] like Figure 2 The illustrated process for the comprehensive recycling and utilization of wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing includes the following steps:

[0076] Step (1): The wastewater from wafer cutting, grinding and polishing in the semiconductor process is treated by solid-liquid separation through a primary cluster filter. Fine particles are deposited on the surface of the filter element of the primary cluster filter to form a filter cake layer. The permeate enters the dynamic ceramic membrane filtration system for treatment.

[0077] Step (2): The clear liquid produced after being processed by the dynamic ceramic membrane filtration system is tested and qualified before entering the clear water tank for further processing. If it fails to meet the requirements, it will enter the primary cluster filter for further processing. The resulting concentrated liquid will be returned to the primary cluster filter for further processing.

[0078] Step (3): After multiple cycles of processing, all the concentrated liquid generated by the dynamic ceramic membrane filtration system is discharged into the first-stage bundled filter for final solid-liquid separation. The filter cake layer is then dehydrated and dried in situ until the moisture content of the filter cake layer is less than 30%. Automatic slag discharge is then performed to recover the fine particles.

[0079] Step (4): The water from the clear water tank in step (2) is purified by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water for later use. The concentrated water generated by the reverse osmosis system is returned to the primary cluster filter for circulation treatment, and finally solid-liquid separation is achieved.

[0080] The filter element of the dynamic ceramic membrane filtration system is a ceramic membrane. The separation layer of the ceramic membrane has hydrophilic properties due to the presence of titanium oxide and high bending hardness due to the presence of zirconium oxide.

[0081] The filter element surface of the primary cluster filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the primary cluster filter and reduce the moisture content of the filter cake layer.

[0082] In addition, the concentrate outlet of the primary cluster filter can also be connected to a secondary cluster filter, the primary cluster filter having a higher throughput than the secondary cluster filter. In step (3), the concentrate from the primary cluster filter enters the secondary cluster filter for in-situ dehydration and drying until the moisture content of the filter cake layer is less than 30%, at which point automatic slag discharge is performed to recover the fine particles.

[0083] In this embodiment, a primary cluster filter and a dynamic ceramic membrane filtration system are used to independently collect solid residue and separate solids and liquids, respectively. The primary cluster filter mainly intercepts most of the solid particles in the wastewater, resulting in a stable concentration of the clarified liquid. This reduces the problem in Examples 1-2 where the direct entry of wastewater into the dynamic ceramic membrane filtration system caused a rapid decrease in the ceramic membrane flux due to increased concentration. It also reduces the risk of large particles in the wastewater causing wear on the mechanical seals of the dynamic ceramic membrane filtration system. The secondary cluster filter is mainly used for collecting dry solid residue and can operate intermittently, reducing the working pressure on the primary cluster filter. This allows the primary cluster filter to focus on solid-liquid separation, eliminating the need for frequent valve opening and closing for in-situ dehydration and reducing valve wear.

[0084] The difference between this embodiment and the processes shown in Embodiments 1 and 2 lies in the selection of different processes based on the particle size of the fine particles in the wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing. When the particle size of the fine particles in the wastewater is less than 1 μm, the process shown in Embodiment 1 or 2 is used; when the particle size of the fine particles is not less than 1 μm, the process shown in this embodiment is used. Both methods can effectively solve the problems of recovering fine particles from wastewater and purifying and reusing water resources.

[0085] The wastewater resource recovery and utilization process described in this invention is not limited to wastewater generated from wafer dicing, grinding, and polishing processes in semiconductor manufacturing; it is applicable to other waste liquids containing fine particles, such as titanium dioxide wastewater and washing solutions for lithium battery material powders like lithium iron phosphate. This wastewater resource recovery and utilization process effectively solves problems such as the difficulty in recovering micro- and nano-sized particles from waste liquids and the inability to dry them in situ. Example

[0086] like Figures 3-9 As shown, the present invention also discloses a method for preparing a ceramic membrane. The ceramic membrane prepared by this method, as a filter element of a dynamic ceramic membrane filtration system, has high precision, high membrane surface hardness, low surface roughness, longer membrane life and better anti-fouling performance, and can be applied to the treatment of high hardness, ultra-wear-resistant, and ultra-fine powder semiconductor wastewater.

[0087] A method for preparing a ceramic membrane for the comprehensive recycling of wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing processes includes the following steps:

[0088] Micron-sized alumina powder, sintering aid, pore-forming agent, dispersant, and binder are mixed in proportion and ball-milled for 4–6 hours to form a slurry. The slurry is then produced by spray granulation and dry pressing to form a support layer preform. After drying to remove the moisture, the preform is fired. During the firing process at 200℃–650℃, the pore-forming agent, binder, and other substances decompose, and the generated gas causes a porous structure to appear inside and on the surface of the fired support layer, thus improving the membrane's performance in wastewater filtration.

[0089] The alumina powder has a median particle size D (50) of 5-30 μm, and the components are mixed in the following proportions: the sintering aid is titanium dioxide (0.5-1.25 wt%), silicon dioxide (2-5 wt%), or magnesium oxide (0.5-2.5 wt%); the pore-forming agent is one or more of starch (3-8 wt%), carbon powder (1-7 wt%), and cellulose (1.5-5 wt%); the dispersant is one or two of sodium hexametaphosphate and PEG (2-4 wt%); and the binder is a 10-15% polyvinyl alcohol solution (2-5 wt%).

[0090] During the sintering process, the sintering aid changes from solid to liquid. This liquid-phase sintering can promote grain rearrangement and enhance the contact between grains, thereby increasing grain boundary mobility, promoting the development of fine grains, and increasing the strength of the support.

[0091] Micron-sized alumina powder, sintering aid, grinding aid, dispersant, and binder are mixed in proportion and ball-milled for 6-8 hours to prepare an intermediate layer film slurry. After coating, drying, and firing, an intermediate layer of film is formed.

[0092] In step (2), the median particle size D (50) of the alumina powder is 5-10 μm; the components are mixed in the following proportions: the sintering aid is silicon dioxide (5-10 wt%), the grinding aid is sodium hexametaphosphate (0.5-1.5 wt%), the dispersant is PEG (1-2 wt%), and the binder is a 2-5% PVA solution (0.2-0.8 wt%).

[0093] The ceramic film prepared in this step has an intermediate layer pore size of 0.2–2 μm, a roughness Ra of 2.5–10 μm, and a Mohs hardness HM of 3–4.

[0094] Nano-alumina powder, sintering aid, binder, and zirconium oxide sol are mixed evenly in a certain proportion to form a separation layer slurry, which is then coated, dried, and fired to form a membrane separation layer.

[0095] Among them, the median particle size D (50) of the alumina powder is 0.1-1 μm, and the components are mixed in the following proportions: the sintering aid is titanium dioxide (10-15 wt%), the binder is a 5-10% PVA solution (2-5 wt%), and the zirconium oxide sol (2-10 wt%).

[0096] The ceramic membrane prepared in this step has a separation layer pore size of 50–80 nm, a roughness Ra of 0.2–0.4 μm, and a Mohs hardness HM of 8–9.

[0097] The ceramic membrane prepared by the above method is the filter element of the dynamic ceramic membrane filtration system in Examples 1-3.

[0098] The ceramic membrane prepared by the method of the present invention has a separation layer in which water molecules adsorbed in water are dissociated due to the presence of titanium oxide. Compared with the sintering aids used in other methods, it is easier to form hydroxyl groups on the surface, which enhances the hydrophilicity, improves the permeability of water molecules, and increases the filtration flux.

[0099] The added zirconia sol can significantly improve the hardness and bonding strength of the film, achieving a Mohs hardness of 8-9. The main principle is that tetragonal zirconia induces phase transformation toughening and microcrack toughening during high-temperature sintering. When treating high-hardness wastewater such as semiconductor silicon powder, silicon carbide, and diamond, the high-hardness, high-wear-resistant coating can have a longer working effect.

[0100] The added zirconia sol, due to its toughening mechanism, also reduces defects on the membrane surface, making the membrane surface smoother with a roughness of Ra0.2-0.4um. During operation, fine nanoparticles are less likely to adhere to the surface and cause membrane flux attenuation, and the flux recovery is significant after backwashing.

[0101] The ceramic membranes prepared by this method have a high flexural strength, ranging from 65 to 180 MPa. Because they need to rotate at a specific speed and use centrifugal force to remove contaminants from the membrane surface during operation, dynamic ceramic membranes require even higher strength compared to those used for static filtration.

[0102] like Figures 3-5 As shown, the ceramic membrane support layer and separation layer prepared by the present invention are more compact, with uniform pore sizes concentrated between 52 and 57 nm, resulting in higher filtration accuracy.

[0103] Therefore, this ceramic membrane possesses high precision, high membrane surface hardness, low surface roughness, and a longer membrane layer (i.e., separation layer) with superior antifouling performance. When applied to high-hardness, ultra-wear-resistant, and ultrafine semiconductor wastewater treatment projects, it offers higher separation accuracy, stronger mechanical properties, and more stable and larger throughput. The combination of this dynamic ceramic membrane filtration system with a cluster filter ensures stable system operation, high separation accuracy, stable throughput, and centralized recovery of semiconductor fine particles and pure water. The system also boasts lower energy consumption and complies with national carbon emission standards.

[0104] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

[0105] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A comprehensive recycling process for wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing, characterized in that, Includes the following steps: Step (1): The wastewater from wafer cutting, grinding and polishing in the semiconductor process is treated by solid-liquid separation through a dynamic ceramic membrane filtration system. The resulting clear liquid is tested and qualified before entering the clear water tank for further treatment. If it is not qualified, solid-liquid separation is performed again and the resulting concentrated liquid enters the concentrated liquid tank. Step (2): The concentrate from step (1) is passed into a cluster filter for secondary solid-liquid separation. Fine particles are deposited on the surface of the filter element of the cluster filter to form a filter cake layer, while the permeate is returned to the dynamic ceramic membrane filtration system for recirculation. Step (3): After multiple cycles of processing, all the concentrated liquid generated by the dynamic ceramic membrane filtration system is discharged into the bundled filter for final solid-liquid separation. The filter cake layer is dehydrated and dried in situ until the moisture content of the filter cake layer is less than 30%. Automatic slag discharge is then performed to recover the fine particles. Step (4): The water from the clear water tank in step (1) is purified by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water for later use. The concentrated water generated by the reverse osmosis system is recycled to the dynamic ceramic membrane filtration system for further processing, and finally solid-liquid separation is achieved. The filter element of the dynamic ceramic membrane filtration system is a ceramic membrane. The separation layer of the ceramic membrane has hydrophilic properties due to the presence of titanium oxide and high bending hardness due to the presence of zirconium oxide. The filter element surface of the cluster filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the cluster filter and reduce the moisture content of the filter cake layer.

2. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing according to claim 1, characterized in that, In step (1), the clear liquid generated by the dynamic ceramic membrane filtration system enters the clear water tank for further treatment when the turbidity is detected to be less than 0.3 NTU.

3. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing according to claim 2, characterized in that, The composition of the fine particles is any one of Si, Ce, SiC, CdTe, GaAs, InP, CdS, GaAlAs, and GaAsP.

4. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing according to claim 2, characterized in that, The operating pressure of the dynamic ceramic membrane filtration system is 0.01–0.2 MPa, the filtration accuracy of the ceramic membrane is 5–200 nm, and its rotation speed is 50–500 Hz.

5. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing according to claim 4, characterized in that, The working pressure of the cluster filter is 0.2 to 1 MPa, and the filtration accuracy of the filter element of the cluster filter is 0.2 to 1 μm.

6. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing according to claim 1, characterized in that, The wastewater in step (1) is first subjected to ultrasonic pretreatment and then filtered and separated by a dynamic ceramic membrane filtration system.

7. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing according to claim 6, characterized in that, The ultrasonic treatment has a frequency of 20–60 kHz and an intensity of 2.0–10.0 kW.

8. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing according to claim 6, characterized in that, When the median particle size D(50) of the fine particles in the wastewater is less than 50 nm, ultrasonic pretreatment is performed.

9. A comprehensive recycling process for wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing, characterized in that: Includes the following steps: Step (1): The wastewater from wafer cutting, grinding and polishing in the semiconductor process is treated by solid-liquid separation through a primary cluster filter. Fine particles are deposited on the surface of the filter element of the primary cluster filter to form a filter cake layer. The permeate enters the dynamic ceramic membrane filtration system for treatment. Step (2): The clear liquid produced after being processed by the dynamic ceramic membrane filtration system is tested and qualified before entering the clear water tank for further processing. If it fails to meet the requirements, it will enter the primary cluster filter for further processing. The resulting concentrated liquid will be returned to the primary cluster filter for further processing. Step (3): After multiple cycles of processing, all the concentrated liquid generated by the dynamic ceramic membrane filtration system is discharged into the first-stage bundled filter for final solid-liquid separation. The filter cake layer is then dehydrated and dried in situ until the moisture content of the filter cake layer is less than 30%. Automatic slag discharge is then performed to recover the fine particles. Step (4): The water from the clear water tank in step (2) is purified by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water for later use. The concentrated water generated by the reverse osmosis system is returned to the primary cluster filter for circulation treatment, and finally solid-liquid separation is achieved. The filter element of the dynamic ceramic membrane filtration system is a ceramic membrane. The separation layer of the ceramic membrane has hydrophilic properties due to the presence of titanium oxide and high bending hardness due to the presence of zirconium oxide. The filter element surface of the primary cluster filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the primary cluster filter and reduce the moisture content of the filter cake layer.

10. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing according to claim 9, characterized in that, The concentrated liquid outlet of the primary cluster filter is also connected to a secondary cluster filter. The processing capacity of the primary cluster filter is higher than that of the secondary cluster filter. In step (3), the concentrated liquid from the primary cluster filter enters the secondary cluster filter for in-situ dehydration and drying until the moisture content of the filter cake layer is less than 30%, and then the filter cake layer is automatically discharged to recover the fine particles.

11. The comprehensive recycling process for wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing processes according to claim 1 or 9, characterized in that, When the particle size of the wastewater is less than 1 μm, the process described in claim 1 shall be used; when the particle size of the wastewater is not less than 1 μm, the process described in claim 9 shall be used.

12. A method for preparing a ceramic film for the comprehensive recycling of wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing processes, characterized in that, Includes the following steps: Step (1): Prepare the support layer Micron-sized alumina powder, sintering aid, pore-forming agent, dispersant, and binder are mixed in proportion and ball-milled for 4-6 hours to form a slurry. The slurry is then produced by spray granulation and dry pressing to form a support layer preform. After drying to remove moisture, it is then fired. Step (2): Prepare the intermediate layer Micron-sized alumina powder, sintering aid, grinding aid, dispersant, and binder are mixed in proportion and ball-milled for 6-8 hours to prepare an intermediate layer film slurry. After coating, drying, and firing, an intermediate layer of film is formed. The ceramic film prepared in this step has an intermediate layer pore size of 0.2–2 μm, a roughness Ra of 2.5–10 μm, and a Mohs hardness HM of 3–4. Step (3): Preparation of the separation layer Nano-alumina powder, sintering aid, binder, and zirconium oxide sol are mixed evenly in a certain proportion to form a separation layer slurry, which is then coated, dried, and fired to form a membrane separation layer. The separation layer of the ceramic membrane prepared in this step has a pore size of 50–80 nm, a roughness Ra of 0.2–0.4 μm, and a Mohs hardness HM of 8–9. In step (3), the sintering aid is 10-15 wt% titanium dioxide and 2-10 wt% zirconium oxide sol.

13. The method for preparing a ceramic film for the comprehensive recycling of wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing processes, as described in claim 12, is characterized in that... In step (1), the median particle size D (50) of the alumina powder is 5-30 μm; in step (2), the median particle size D (50) of the alumina powder is 5-10 μm; and in step (3), the median particle size D (50) of the alumina powder is 0.1-1 μm.

14. The method for preparing a ceramic film for the comprehensive recycling of wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing processes, as described in claim 13, is characterized in that... In step (1), the sintering aid is 0.5-1.25 wt% titanium dioxide, 2-5 wt% silicon dioxide, or 0.5-2.5 wt% magnesium oxide; the pore-forming agent is one or more of starch (3-8 wt%), carbon powder (1-7 wt%), and cellulose (1.5-5 wt%); the dispersant is one or two of sodium hexametaphosphate and PEG (2-4 wt%); and the binder is a 10-15% polyvinyl alcohol solution (2-5 wt%).

15. The method for preparing a ceramic film for the comprehensive resource recovery of wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing processes, as described in claim 14, is characterized in that... In step (2), the sintering aid is 5-10 wt% silicon dioxide, the grinding aid is 0.5-1.5 wt% sodium hexametaphosphate, the dispersant is 1-2 wt% PEG, and the binder is 0.2-0.8 wt% PVA solution with a concentration of 2-5%.

16. The method for preparing a ceramic film for the comprehensive recycling of wastewater from wafer dicing, grinding, and polishing in semiconductor manufacturing processes, as described in claim 15, is characterized in that... In step (3), the adhesive is 2-5 wt% of a prepared PVA solution with a concentration of 5-10%.

17. The method for preparing a ceramic film for the comprehensive recycling of wafer dicing, grinding, and polishing wastewater in semiconductor manufacturing processes, according to any one of claims 12 to 16, is characterized in that... The ceramic membrane is the filter element of the dynamic ceramic membrane filtration system according to any one of claims 1 to 10.

Images