Process for resource comprehensive recycling of wafer cutting, grinding and polishing wastewater in semiconductor manufacturing process

Abstract

The present invention provides a process for the resource comprehensive recycling of wafer cutting, grinding and polishing wastewater in a semiconductor manufacturing process. Solid-liquid separation treatment is carried out via a dynamic ceramic membrane filtration system and a cluster filter in sequence without any chemical reagent added, and after being tested to meet standards, the resulting clear liquid is purified via a UF system and / or an RO system, so as to achieve the recycling of wastewater in a semiconductor manufacturing process. Also provided is a method for preparing a ceramic membrane used for the process. The ceramic membrane has hydrophilic properties due to the presence of titanium oxide and has high flexural strength and a high wear resistance coefficient due to the presence of zirconium oxide, and the ceramic membrane has fouling resistance, anti-clogging performance, and high filtration precision due to surface coating modification. The process involves directly performing solid-liquid separation while recycling solid and liquid phases. Recycled semiconductor fine particles do not contain other impurities and chemical agent residues, and are directly subjected to in-situ concentrated pneumatic dewatering, drying, and bagging in the cluster filter, facilitating recycling and transportation. The recycling rate of wastewater is higher than 97%, and the recycling rate of the semiconductor fine particles is higher than 98%.

Description

Wafer cutting, grinding and polishing wastewater resource comprehensive recycling process in semiconductor process TECHNICAL FIELD

[0001] The present application relates to the technical field of waste liquid treatment in the wafer material processing process of the semiconductor industry, and particularly relates to a wafer cutting, grinding and polishing wastewater resource comprehensive recycling process in semiconductor process. BACKGROUND

[0002] In the semiconductor product manufacturing industry, during the cutting, grinding and polishing processing of wafer or wafer material, the basic water for production process is high-purity water, and a large amount of high-purity water is consumed in the whole process. During the cutting, grinding and polishing processing, part of the semiconductor material (mainly wafer or wafer) is removed, and these materials are distributed in the high-purity water in the form of fine powder. Since there are few other impurities in such water, high-purity water and fine semiconductor material powder are both resource products with high value. In order to maintain and realize their value, a resource treatment process without using any chemical agent is needed to separate and reuse them.

[0003] At present, the cutting, grinding and polishing wastewater of semiconductor wafer / wafer material contains a large amount of fine semiconductor material powder. According to the category of semiconductor materials, there are Si, Ce, CdTe, GaAsP, etc. Due to different processes and different processes, the particle size distribution is between nanometers, sub-nanometers and microns. Among them, the fine semiconductor material powder in the form of nano and sub-micron particles has a large surface energy, forms a stable solid-liquid mixed system with water, and remains stable for a long time without settling and gathering. The commonly used method is to use chemical agents to break the stability, gather, flocculate and separate the solid-liquid, but this method cannot recycle clean water and fine semiconductor material powder. For example, Chinese patent CN201910648428.X discloses a semiconductor grinding wastewater treatment method, which uses the method of adding chemical reagents (flocculants, coagulants) for sedimentation treatment. For example, Chinese patent CN201910730408.7 discloses a semiconductor wastewater treatment method, which also uses the method of adding chemical reagents to agglomerate the suspended solids, and then uses a filtration separation device for solid-liquid separation to realize the treatment of wastewater. However, these methods consume a large amount of chemical reagents, cannot be treated again, and the obtained fine semiconductor material powder and water cannot be used again, resulting in secondary pollution.

[0004] In addition, some people also use filters to directly treat these wastewater, although it can be treated by multiple filtering, without secondary pollution, but the process is too long, the filtering precision is not enough, the treatment capacity is limited, and the fine powder of semiconductor materials is difficult to collect. For example, Chinese patent CN201621421971.4 discloses a semiconductor industry grinding and cutting wastewater recycling device, which uses multiple sets of equipment for multiple filtering treatment, the whole treatment device process line is too long, the treatment capacity is unstable, and the system is difficult to stably and continuously run.

[0005] For the selection of filtering equipment, the commonly used filtering elements are hollow fiber membrane or tubular ceramic membrane. Although the filtering precision of hollow fiber membrane and tubular ceramic membrane is high, the filtering elements themselves are static in operation. It is found in engineering practical application cases that the wastewater containing fine powder of semiconductor materials, colloidal particles and angular particulate substances cause sharp decline of static membrane flux, serious pollution or damage of membrane, membrane is easy to be blocked, frequent cleaning is required, a large amount of chemicals are consumed, cleaning wastewater becomes regenerated wastewater, water recovery rate is not high, and fine powder of semiconductor materials cannot be recovered.

[0006] Therefore, the improvement of the filtering element is the key to solve such problems. For example, Chinese patent CN201811170407.3 discloses a batch complete filtering process of API liquid in the pre-crystal transfer process of pharmaceutical production, which mentions that the rotating ceramic membrane is used for filtering treatment of fine particles. Compared with static tubular ceramic membrane, it has better performance in terms of not easy to be blocked and maintaining stable flux, but for wastewater containing fine powder of semiconductor materials with high hardness and angular particulate substances, the membrane surface is easy to be damaged, the filtering precision is invalid, and normal filtration cannot be realized; the ultra-fine powder with a particle size distribution of 5nm-60nm and colloidal particles pollute the membrane surface, block the membrane holes, cause sharp decline of flux, the treatment system cannot continuously and stably run, and the recovery rate of clean water and fine powder of semiconductor materials is not high.

[0007] Therefore, it is necessary to improve the wastewater treatment method in the semiconductor process in the prior art to solve the above problems.

[0008] SUMMARY

[0009] The purpose of the present application is to disclose a wafer cutting, grinding and polishing wastewater resourceization comprehensive recycling process in a semiconductor process, which does not use any chemical agent, can maintain the cleanliness of fine particles of semiconductor materials, realizes nanoscale high-precision solid-liquid separation by using a dynamic ceramic membrane filtering system, and realizes in-situ dewatering and drying treatment by using a cluster filter, and concentrates the recovery of fine particles of semiconductor materials and water resources.

[0010] To achieve the above purpose, the present application provides a wafer cutting, grinding and polishing wastewater resourceization comprehensive recycling process in a semiconductor process, comprising the following steps:

[0011] Step (1): The semiconductor process wafer cutting, grinding, polishing wastewater is subjected to solid-liquid separation treatment by a dynamic ceramic membrane filtration system, and the clear liquid produced is detected to be qualified and then enters a clear water tank for treatment, or is subjected to solid-liquid separation treatment again if unqualified, and the concentrated liquid produced enters a concentrated liquid tank;

[0012] Step (2): The concentrated liquid in step (1) is introduced into a cluster filter for secondary solid-liquid separation treatment, and the fine particles are deposited on the surface of the filter element of the cluster filter to form a filter cake layer, and the permeate is returned to the dynamic ceramic membrane filtration system for recycling treatment;

[0013] Step (3): After multiple cycles of treatment, the concentrated liquid produced by the dynamic ceramic membrane filtration system is all discharged into the cluster filter for final solid-liquid separation treatment, and the filter cake layer is subjected to in-situ dewatering and drying treatment until the water content of the filter cake layer is less than 30%, and the fine particles are recovered;

[0014] Step (4): The water in the clear water tank in step (1) is subjected to purification treatment by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water for collection, and the concentrated water produced by the reverse osmosis system is returned to the dynamic ceramic membrane filtration system for recycling treatment, and finally solid-liquid separation is achieved;

[0015] In the above method, the filter element of the dynamic ceramic membrane filtration system is a ceramic membrane, and the separation layer of the ceramic membrane has hydrophilic properties due to the presence of titanium oxide and has high bending hardness due to the presence of zirconium oxide.

[0016] The surface of the filter element of the cluster filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the cluster filter and reduce the water content of the filter cake layer.

[0017] In some embodiments, the clear liquid produced by the dynamic ceramic membrane filtration system in step (1) enters the clear water tank for treatment when the turbidity detected is less than 0.3 NTU.

[0018] In some embodiments, the composition of the fine particles is any one of Si, Ce, SiC, CdTe, GaAs, InP, CdS, GaAlAs, and GaAsP.

[0019] In some embodiments, the operating pressure of the dynamic ceramic membrane filtration system is 0.01-0.2 MPa, the filtration precision of the ceramic membrane is 5-200 nm, and the rotational speed is 50-500 Hz.

[0020] In some embodiments, the working pressure of the cluster filter is 0.2-1 MPa, and the filtration precision of the filter element of the cluster filter is 0.2-1 μm.

[0021] In some embodiments, the wastewater of step (1) is first subjected to ultrasonic pretreatment and then filtered and separated by a dynamic ceramic membrane filtration system.

[0022] In some embodiments, the ultrasonic treatment has a frequency of 20-60 kHz and an intensity of 2.0-10.0 kW.

[0023] In some embodiments, when the median particle size D(50) of the fine particles in the wastewater is less than 50 nm, the wastewater is subjected to ultrasonic pretreatment.

[0024] To achieve the above-mentioned purpose, the application further provides a wafer cutting, grinding and polishing wastewater resource comprehensive recycling process in a semiconductor process, comprising the following steps:

[0025] Step (1): The wafer cutting, grinding and polishing wastewater in a semiconductor process is subjected to solid-liquid separation treatment by a primary bundled filter, fine particles are deposited on the surface of the filter element of the primary bundled filter to form a filter cake layer, and the permeate enters a dynamic ceramic membrane filtration system for treatment;

[0026] Step (2): The clear liquid produced after the treatment by the dynamic ceramic membrane filtration system is detected, and if it is qualified, it enters a clean water tank for treatment, and if it is unqualified, it enters the primary bundled filter again for treatment, and the concentrated liquid produced is returned to the primary bundled filter for treatment;

[0027] Step (3): After multiple cycles of treatment, the concentrated liquid produced by the dynamic ceramic membrane filtration system is all discharged into the primary bundled filter for final solid-liquid separation treatment, and the filter cake layer is subjected to in-situ dewatering and drying treatment until the water content of the filter cake layer is less than 30%, automatic slagging work is performed, and fine particles are recovered;

[0028] Step (4): The water in the clean water tank of step (2) is subjected to purification treatment by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water for collection, and the concentrated water produced by the reverse osmosis system is returned to the primary bundled filter for recycling treatment, and finally solid-liquid separation is achieved;

[0029] The filter element of the dynamic ceramic membrane filtration system is a ceramic membrane, and the separation layer of the ceramic membrane has hydrophilic properties due to the presence of titanium oxide and has high bending hardness due to the presence of zirconium oxide.

[0030] The surface of the filter element of the primary bundled filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the primary bundled filter and reduce the water content of the filter cake layer.

[0031] In some embodiments, the concentrated liquid outlet of the primary cluster filter is further connected with a secondary cluster filter, the processing capacity of the primary cluster filter is higher than that of the secondary cluster filter; the concentrated liquid of the primary cluster filter in step (3) enters the secondary cluster filter for in-situ dewatering and drying treatment until the moisture content of the filter cake layer is less than 30%, and the automatic deslagging work is performed to recover the fine particles.

[0032] In some embodiments, when the particle size of the fine particles in the wastewater is less than 1 μm, the process of claim 1 is selected; when the particle size of the fine particles in the wastewater is not less than 1 μm, the process of claim 9 is selected.

[0033] The second object of the application is to disclose a ceramic membrane preparation method, which is used as a filtering element of a dynamic ceramic membrane filtration system, has high precision, high membrane surface hardness, low surface roughness, longer service life and better anti-pollution performance of the membrane layer, and can be applied to high hardness, super wear-resistant and ultra-fine powder semiconductor wastewater treatment.

[0034] To achieve the above object, the application provides a ceramic membrane preparation method for comprehensive recovery of wafer cutting, grinding and polishing wastewater in semiconductor processing, comprising the following steps:

[0035] Step (1): preparation of a support layer

[0036] The micron alumina powder, sintering aids, pore-forming agents, dispersants and binders are mixed in proportion and ball milled for 4-6 h to prepare a slurry, and then the slurry is subjected to a spray granulation and dry pressing process to prepare a support layer blank, and after drying, the support layer blank is subjected to a sintering treatment;

[0037] Step (2): preparation of an intermediate layer

[0038] The micron alumina powder, sintering aids, grinding aids, dispersants and binders are mixed in proportion and ball milled for 6-8 h to prepare an intermediate layer membrane slurry, and after coating, drying and sintering, the intermediate layer membrane slurry forms an intermediate layer of the membrane;

[0039] The intermediate layer of the ceramic membrane prepared in this step has a pore size of 0.2-2 um, a roughness Ra of 2.5-10 um and a Mohs hardness HM of 3-4;

[0040] Step (3): preparation of a separation layer

[0041] The nano alumina powder, sintering aids, binders and zirconia sol are uniformly stirred in proportion to prepare a separation layer slurry, and after coating, drying and sintering, the separation layer slurry forms a separation layer of the membrane;

[0042] 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 um and a Mohs hardness HM of 8-9.

[0043] In some embodiments, the median particle size D(50) of the alumina powder in step (1) is 5-30 um, the median particle size D(50) of the alumina powder in step (2) is 5-10 um; the median particle size D(50) of the alumina powder in step (3) is 0.1-1 um.

[0044] In some embodiments, the sintering aid in step (1) is titanium oxide (0.5-1.25 wt%) or silicon oxide (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%), cellulose (1.5-5 wt%), the dispersing agent is one or both 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%).

[0045] In some embodiments, the sintering aid in step (2) is silicon oxide (5-10 wt%), the grinding aid is sodium hexametaphosphate (0.5-1.5 wt%), the dispersing agent is PEG (1-2 wt%), and the binder is a PVA solution with a configured concentration of 2-5% (0.2-0.8 wt%).

[0046] In some embodiments, the sintering aid in step (3) is titanium oxide (10-15 wt%), the binder is a PVA solution with a configured concentration of 5-10% (2-5 wt%), and zirconium oxide sol (2-10 wt%).

[0047] In some embodiments, the ceramic membrane is a filter element of the dynamic ceramic membrane filtration system described above.

[0048] Compared with the prior art, the present application has the following advantages: (1) no chemical reagents are added, no PH adjustment is performed by using chemical reagents, direct solid-liquid separation is performed, and both solid and liquid phases are recovered; (2) the recovered water has small turbidity and contains no other impurities and chemical reagent residues, and can be directly used as feed water for UF and / or RO systems for purification treatment, the recovered semiconductor fine particles contain no other impurities and chemical reagent residues, and are directly subjected to air pressure dewatering and drying for bagging without using energy-consuming processes such as evaporation and drying, which is beneficial to recycling and convenient for transportation, the wastewater recovery rate is higher than 97%, and the semiconductor fine particle recovery rate is higher than 98%; (3) the ceramic membrane has hydrophilic properties due to the presence of titanium oxide, has high bending hardness and high wear resistance coefficient due to the presence of zirconium oxide, has a modified surface coating layer that is resistant to pollution and not easy to be blocked, has high precision, and has high mechanical strength. BRIEF DESCRIPTION OF DRAWINGS

[0049] FIG. 1 is a process diagram of the comprehensive recycling and utilization of wafer cutting, grinding and polishing wastewater in semiconductor processing according to Examples 1-2;

[0050] Figure 2 is a semiconductor wafer cutting, grinding and polishing wastewater resource comprehensive recycling process diagram shown in Example 3;

[0051] Figure 3 is a SEM diagram of the support layer of the ceramic membrane shown in the present application;

[0052] Figure 4 is a SEM diagram of the separation layer of the ceramic membrane shown in the present application;

[0053] Figure 5 is a pore size distribution diagram of the ceramic membrane shown in the present application;

[0054] Figure 6 is a flux decay comparison curve diagram of the ceramic membrane shown in the present application and the prior art ceramic membrane;

[0055] Figure 7 is a comparison diagram of pure water and wastewater after treatment by the process shown in the present application;

[0056] Figure 8 is a semiconductor micro-particle diagram after treatment by the process shown in the present application;

[0057] Figure 9 is a dynamic ceramic membrane filtration system engineering flux monitoring distribution diagram shown in the present application. DETAILED DESCRIPTION

[0058] The present application will be described in detail below in conjunction with the embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not a limitation on the present application, and equivalent transformations or substitutions of function, method or structure made by those of ordinary skill in the art based on these embodiments are within the scope of the present application.

[0059] Example 1

[0060] As shown in Figures 1, 3-9, a semiconductor wafer cutting, grinding and polishing wastewater resource comprehensive recycling process includes the following steps:

[0061] Step (1): The semiconductor wafer cutting, grinding and polishing wastewater is subjected to solid-liquid separation treatment by a dynamic ceramic membrane filtration system, and the clear liquid produced is detected for qualification and then enters a clear water tank for treatment. If it is not qualified, it is subjected to solid-liquid separation treatment again, and the concentrated liquid produced enters a concentrated liquid tank;

[0062] Step (2): The concentrated liquid in step (1) is introduced into a cluster filter for secondary solid-liquid separation treatment, and the micro-particles are deposited on the surface of the filter element of the cluster filter to form a filter cake layer, and the permeate is returned to the dynamic ceramic membrane filtration system for recycling treatment;

[0063] Step (3): After multiple cycles of treatment, the concentrated liquid produced by the dynamic ceramic membrane filtration system is discharged into the cluster filter for final solid-liquid separation treatment, and the filter cake layer is treated in situ for dewatering and drying until the moisture content of the filter cake layer is less than 30%, and the automatic discharge work is carried out, and the fine particles are recovered;

[0064] Step (4): The water in the water tank in step (1) is purified by the ultrafiltration system and / or the reverse osmosis system to obtain high-purity water for collection, and the concentrated water produced by the reverse osmosis system is returned to the dynamic ceramic membrane filtration system for recycling treatment, and finally the solid-liquid separation is realized;

[0065] Among them, the filter element of the dynamic ceramic membrane filtration system is a ceramic membrane, and 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;

[0066] The surface of the filter element 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.

[0067] In this embodiment, the clear liquid produced by the dynamic ceramic membrane filtration system is detected by an online intelligent tester (including but not limited to a turbidity meter and a conductivity meter) to be qualified in water quality, and then enters the water tank for use as the UF system and / or OR system inlet water. If it is unqualified, it will return to the dynamic ceramic membrane filtration system. Only when the clear liquid produced by the dynamic ceramic membrane filtration system in step (1) is detected to have a turbidity less than 0.3 NTU is it allowed to enter the water tank for further purification treatment.

[0068] The fine particles in the present application are any one of Si, Ce, SiC, CdTe, GaAs, InP, CdS, GaAlAs, GaAsP, but are not limited thereto. As long as the fine particles generated in the semiconductor process subtractive machining process can be treated using the process. It should be noted that the wastewater in the semiconductor process contains fine particles of any one of the above components, and if multiple components are contained, although they can be recovered, they cannot be further classified and recovered. Therefore, the treatment process disclosed in this embodiment is mainly applied to wastewater containing a single component.

[0069] In the process, the wastewater generated in the semiconductor process is first collected in a water collecting tank to achieve homogeneity, buffering and stability. The operating pressure of the dynamic ceramic membrane filtration system is 0.01-0.2 MPa, the filtration precision of the ceramic membrane is 5-200 nm, and the rotating speed is 50-500 Hz; the working pressure of the bundle filter is 0.2-1 MPa, and the filtration precision of the filtration element of the bundle filter is 0.2-1 μm. In practical application, different process parameters are selected according to the content of the particles in the wastewater in the semiconductor process to achieve the best treatment effect, but the operating parameters of the dynamic ceramic membrane filtration system and the bundle filter are selected within the above numerical range, and the backwashing process of the dynamic ceramic membrane filtration system can be appropriately selected.

[0070] As shown in FIGS. 6 and 9, the ceramic membrane flux of the present application is higher than that of the ordinary ceramic membrane in the prior art (such as the ceramic membrane disclosed in Chinese patent CN201811170407.3), the performance is more stable, and the flux attenuation is slower under the same conditions for 10 days. In the present embodiment, five ceramic membranes are configured in a single dynamic ceramic membrane filtration system, and the flux shown in FIG. 6 is tested and compared for a single dynamic ceramic membrane filtration system. As shown in FIG. 9, when multiple dynamic ceramic membrane filtration systems are used at the same time, the flux attenuation changes little under full load for 1 day. It can be seen that the ceramic membrane and the dynamic ceramic membrane filtration system prepared by the present application have more stable and reliable performance, higher processing capacity and longer service life.

[0071] The ceramic membrane has strong hydrophilicity, high bending hardness, stronger resistance to pollution, high mechanical strength, higher and more stable flux. The concentrated liquid separated by the dynamic ceramic membrane filtration system enters the bundle filter for secondary solid-liquid separation. The surface of the filtration element of the bundle filter is covered with a nanofiber membrane, and the pore size and porosity of the nanofiber membrane are higher than those of the filtration medium inside the filtration element, so that the fine particles can quickly deposit on the surface of the nanofiber membrane to form a filter cake layer, and water can quickly permeate. By controlling the controller of the bundle filter, the filter cake layer can be in-situ gas purged and / or washed with clean water. After washing and drying the filter cake layer, the filtration medium of the filtration element is expanded by back blowing and / or vibration, the filter cake layer is cracked, and automatic deslagging is realized.

[0072] The recovery rate of the wastewater treated by the process is higher than 97%, and the recovery rate of the semiconductor fine particles is higher than 98%.

[0073] Example 2

[0074] In the solid-liquid separation of the wastewater generated in the semiconductor process (including each process of cutting, grinding and polishing), pretreatment can be performed first, and then the wastewater is treated according to the treatment process in Example 1.

[0075] The wastewater of step (1) is first pretreated by ultrasonic wave and then filtered and separated by a dynamic ceramic membrane filtration system. The frequency of the ultrasonic wave is 20-60 kHz, and the intensity is 2.0-10.0 kW.

[0076] The ultrasonic wave pretreatment of the wastewater utilizes the cavitation effect generated when the ultrasonic wave propagates in a medium, causes rapid growth and collapse of microbubbles in the solution, generates strong local disturbance, destroys the stable state of the solid-liquid dispersed phase of the wastewater, promotes the aggregation of microfine particles, facilitates the entry of the microfine particles into the dynamic ceramic membrane filtration system, forms dynamic cross-flow filtration on the surface of the ceramic membrane, and has higher solid-liquid separation efficiency. Meanwhile, the microfine particles are not easy to deposit on the surface of the ceramic membrane.

[0077] The above pretreatment step can be selectively selected according to the size of the microfine particles in the wastewater. When the median particle size D(50) of the microfine particles in the wastewater is less than 50 nm, ultrasonic wave pretreatment is performed. It should be noted that when the microfine particles D(50) in the wastewater is less than 50 nm, ultrasonic wave pretreatment can effectively break the stable system, and the initially destabilized wastewater improves the solid-liquid separation performance of the subsequent dynamic ceramic membrane filtration system. When the microfine particles D(50) in the wastewater is greater than 100 nm, the pretreatment has no obvious effect on the solid-liquid separation performance of the subsequent dynamic ceramic membrane filtration system, and the wastewater can be directly treated by the dynamic ceramic membrane filtration system without ultrasonic wave pretreatment.

[0078] Example 3

[0079] The wafer cutting, grinding and polishing wastewater resource comprehensive recycling process in the semiconductor process shown in FIG. 2 includes the following steps:

[0080] Step (1): The wafer cutting, grinding and polishing wastewater in the semiconductor process is subjected to solid-liquid separation treatment by a primary bundled filter, the microfine particles are deposited on the surface of the filter element of the primary bundled filter to form a filter cake layer, and the permeate enters a dynamic ceramic membrane filtration system for treatment;

[0081] Step (2): The clear liquid produced after the treatment by the dynamic ceramic membrane filtration system is detected, and if it is qualified, it is sent to a clean water tank for treatment. If it is not qualified, it is sent to the primary bundled filter for treatment again, and the concentrated liquid produced is returned to the primary bundled filter for treatment;

[0082] Step (3): After multiple cycles of treatment, the concentrated liquid produced by the dynamic ceramic membrane filtration system is all discharged into the primary bundled filter for final solid-liquid separation treatment, and the filter cake layer is subjected to in-situ dewatering and drying treatment until the moisture content of the filter cake layer is less than 30%, and the microfine particles are recovered.

[0083] Step (4): The water in the water tank of step (2) is purified by an ultrafiltration system and / or a reverse osmosis system to obtain high-purity water, and the concentrated water produced by the reverse osmosis system is returned to the primary cluster filter for recycling treatment, and finally solid-liquid separation is achieved;

[0084] The filtration element of the dynamic ceramic membrane filtration system is a ceramic membrane, and 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.

[0085] The surface of the filtration element 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 water content of the filter cake layer.

[0086] In addition, the concentrated liquid outlet of the primary cluster filter can also be connected to a secondary cluster filter, and the processing capacity of the primary cluster filter is higher than that of the secondary cluster filter. The concentrated liquid of the primary cluster filter in step (3) enters the secondary cluster filter for in-situ dewatering and drying treatment until the water content of the filter cake layer is less than 30%, and the automatic deslagging work is carried out to recover the fine particles.

[0087] In this embodiment, the primary cluster filter and the dynamic ceramic membrane filtration system are used to independently collect and separate solid-liquid, respectively. The primary cluster filter is mainly used to intercept most of the solid particles in the wastewater, and the concentration of the clear liquid is stable, which reduces the problem of rapid flux decay of the ceramic membrane caused by the increase in concentration when the wastewater directly enters the dynamic ceramic membrane filtration system in embodiments 1-2. At the same time, it reduces the risk of wear of the heavy mechanical seal of the dynamic ceramic membrane filtration system caused by large particles in the wastewater. The secondary cluster filter is mainly used for the collection of solid-phase dry residue and can be operated intermittently, which reduces the working pressure of the primary cluster filter and makes the primary cluster filter mainly used for solid-liquid separation treatment. Without the need to frequently open and close the valve for in-situ dewatering, the wear of the valve is reduced.

[0088] The difference between the process shown in the embodiment and the processes shown in embodiments 1 and 2 is that different processes are selected according to the particle size of the fine particles in the wafer cutting, grinding and polishing wastewater in the semiconductor process. 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 selected, and when the particle size of the fine particles is not less than 1 μm, the process shown in this embodiment is selected, which can effectively solve the recovery of fine particles in wastewater and the purification and reuse of water resources.

[0089] The wastewater resource comprehensive recycling process shown in the application is not only limited to the wastewater generated in the wafer cutting, grinding and polishing processes in semiconductor processes, but also applicable to other wastewater containing fine particles, such as titanium dioxide wastewater, lithium battery material powder material such as lithium iron phosphate washing liquid and the like. The wastewater resource comprehensive recycling process shown in the application can effectively solve the problems of difficult recovery of micrometer and nanometer particles in wastewater and inability to dry in situ.

[0090] Example 4

[0091] As shown in Figures 3-9, the application also discloses a ceramic membrane preparation method. The ceramic membrane prepared by the method is used as a filter element of a dynamic ceramic membrane filtration system, has high precision, high membrane surface hardness and low surface roughness, the membrane layer has a longer service life and better anti-pollution performance, and can be applied to high hardness, super wear-resistant and ultra-fine powder semiconductor wastewater treatment.

[0092] The ceramic membrane preparation method for semiconductor wafer cutting, grinding and polishing wastewater resource comprehensive recycling includes the following steps:

[0093] Step (1): preparing a support layer

[0094] The micron alumina powder, sintering aid, pore former, dispersant and binder are mixed in proportion and ball milled for 4-6 hours to prepare a slurry, then the slurry is prepared into a support layer blank body through a spray granulation and dry pressing process, dried to remove the water inside, and then sintered. During the sintering process at 200-650 DEG C, the pore former and binder will decompose, and the generated gas will cause the support layer to have a porous structure inside and on the surface after sintering, thereby improving the performance of the membrane in wastewater filtration.

[0095] The alumina powder has a median particle size D(50) of 5-30 um, and the components are mixed in the following proportions: the sintering aid is titanium oxide (0.5-1.25 wt%), silicon oxide (2-5 wt%) or magnesium oxide (0.5-2.5 wt%), the pore former 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 both 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%).

[0096] 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 improving the grain boundary mobility, promoting the growth of fine grains and increasing the strength of the support body.

[0097] Step (2): preparing an intermediate layer

[0098] The micron alumina powder, sintering aid, grinding aid, dispersant and binder are mixed in proportion and ball milled for 6-8 hours to prepare the intermediate layer slurry, and the intermediate layer is formed after coating, drying and firing;

[0099] In the step (2), the median particle size D(50) of the alumina powder is 5-10 um; the components are mixed in the following proportions: the sintering aid is silicon oxide (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 PVA solution with a concentration of 2-5% (0.2-0.8 wt%).

[0100] The intermediate layer of the ceramic membrane prepared in this step has a pore size of 0.2-2 um, a roughness Ra of 2.5-10 um, and a Mohs hardness HM of 3-4.

[0101] Step (3): preparation of the separation layer

[0102] The nano-alumina powder, sintering aid, binder and zirconia sol are stirred uniformly in proportion to prepare the separation layer slurry, and the separation layer is formed after coating, drying and firing.

[0103] In the step (2), the median particle size D(50) of the alumina powder is 5-10 um; the components are mixed in the following proportions: the sintering aid is silicon oxide (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 PVA solution with a concentration of 2-5% (0.2-0.8 wt%).

[0104] 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 um, and a Mohs hardness HM of 8-9.

[0105] The ceramic membrane prepared by the above method is used as the filter element of the dynamic ceramic membrane filtration system in Examples 1-3.

[0106] The ceramic membrane prepared by the method shown in the application has the following advantages: due to the presence of titanium oxide in the separation layer, water molecules are dissociated in water, compared with other sintering aids, hydroxyl groups are more easily formed on the surface, the hydrophilic property is enhanced, the water molecule passing property is good, and the filtration flux is increased.

[0107] The added zirconia sol can significantly improve the hardness and bonding strength of the membrane layer, and the Mohs hardness reaches 8-9. The main principle is that the tetragonal zirconia induces phase change toughening and micro-crack toughening during high-temperature firing, and when treating high-hardness wastewater such as semiconductor silicon powder, silicon carbide and diamond, the high-hardness and high-wear-resistant coating can have a longer effect.

[0108] The added zirconium oxide sol reduces the defects on the membrane surface due to the toughening mechanism, so that the membrane surface is smoother, the roughness reaches Ra0.2-0.4um, and the fine nanoparticles are less likely to adhere to the surface to cause membrane flux attenuation during operation, and the flux is recovered after backwashing.

[0109] The bending strength of the ceramic membrane prepared by the method is 65-180MPa, and the strength is high. Since rotation at a specific speed is required during operation and the pollutants on the membrane surface are removed by centrifugal force, the dynamic ceramic membrane requires higher strength compared to the ceramic membrane for static filtration.

[0110] As shown in Figures 3-5, the ceramic membrane support layer and separation layer prepared by the present application are more dense, the pore sizes are uniformly distributed, and the filtration precision is higher.

[0111] Therefore, the ceramic membrane has high precision, high membrane surface hardness, low surface roughness, longer service life of the membrane layer (i.e. the separation layer), and better anti-pollution performance. When applied to high-hardness, super-wear-resistant, and ultra-fine powder semiconductor wastewater engineering, it has higher separation precision, stronger mechanical properties, more stable and larger flux. The dynamic ceramic membrane filter system combined with the bundle filter processing technology has stable process system operation, high separation precision, stable flux, can concentrate the recovery of semiconductor fine particles and pure water, and lower system energy consumption, which meets the national double carbon requirements.

[0112] The above series of detailed descriptions are only specific descriptions of the feasible embodiments of the present application, and are not intended to limit the protection scope of the present application. Any equivalent embodiments or changes made without departing from the spirit of the present application should be included in the protection scope of the present application.

[0113] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and the skilled person in the art should consider the specification as a whole, and the technical solutions in each embodiment can be combined to form other embodiments that can be understood by the skilled person.

Claims

1. A comprehensive recycling process for wafer cutting, grinding, and polishing wastewater in semiconductor manufacturing, characterized in that, The method comprises the following steps: Step (1): the semiconductor wafer cutting, grinding and polishing wastewater is treated by the dynamic ceramic membrane filtration system for solid-liquid separation, and the clear liquid is detected and qualified to enter the clean water tank for treatment, and if not qualified, the solid-liquid separation treatment is performed again, and the concentrated liquid enters the concentrated liquid tank; Step (2): the concentrated liquid in step (1) is introduced into the cluster filter for secondary solid-liquid separation treatment, and the fine particles are deposited on the surface of the filter element of the cluster filter to form a filter cake layer, and the permeate is returned to the dynamic ceramic membrane filtration system for recycling treatment; Step (3): after multiple cycle treatments, the concentrated liquid produced by the dynamic ceramic membrane filtration system is discharged into the cluster filter for final solid-liquid separation treatment, and the filter cake layer is treated by in-situ dewatering and drying until the water content of the filter cake layer is less than 30%, and the fine particles are recovered; Step (4): the water in the clean water tank in step (1) is purified by the ultrafiltration system and / or the reverse osmosis system to obtain high-purity water for collection, and the concentrated water produced by the reverse osmosis system is returned to the dynamic ceramic membrane filtration system for recycling treatment, and finally the solid-liquid separation is realized; The filter element of the dynamic ceramic membrane filtration system is a ceramic membrane, and 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 surface of the filter element of the cluster filter is covered with a nanofiber membrane to improve the solid-liquid separation efficiency of the cluster filter and reduce the water content of the filter cake layer. 2.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process according to claim 1, wherein, The clear liquid produced by the dynamic ceramic membrane filtration system in step (1) is detected, and when the turbidity is less than 0.3 NTU, it enters the clean water tank for treatment. 3.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process according to claim 2, wherein, The composition of the fine particles is any one of Si, Ce, SiC, CdTe, GaAs, InP, CdS, GaAlAs and GaAsP. 4.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process in a semiconductor process 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 precision of the ceramic membrane is 5-200 nm, and the rotation speed is 50-500 Hz. 5.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process according to claim 4, wherein, The working pressure of the cluster filter is 0.2-1 MPa, and the filtration precision of the filter element of the cluster filter is 0.2-1 μm. 6.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process in a semiconductor process according to claim 1, wherein, The wastewater in step (1) is first pretreated by ultrasonic waves and then filtered and separated by the dynamic ceramic membrane filtration system. 7.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process of claim 6, wherein, The frequency of the ultrasonic treatment is 20-60 kHz, and the intensity is 2.0-10.0 kW. 8.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process of claim 6, wherein, 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 wafer cutting, grinding and polishing wastewater in semiconductor manufacturing, characterized in that, The method comprises the following steps: Step (1): the semiconductor wafer cutting, grinding and polishing wastewater is treated by the dynamic ceramic membrane filtration system for solid-liquid separation, and the clear liquid is detected and qualified to enter the clean water tank for treatment, and if not qualified, the solid-liquid separation treatment is performed again, and the concentrated liquid enters the concentrated liquid tank; Step (2): the clear liquid produced by the dynamic ceramic membrane filtration system is detected and qualified to enter the clean water tank for treatment, and if not qualified, the clear liquid is treated again by the first-stage cluster filter, and the concentrated liquid is returned to the first-stage cluster filter for treatment; Step (3): After multiple cycles of treatment, the concentrated liquid produced by the dynamic ceramic membrane filtration system is discharged into the primary cluster filter for final solid-liquid separation treatment, and the filter cake layer is treated in situ for dehydration and drying until the moisture content of the filter cake layer is less than 30%, and the automatic discharge work is carried out to recover the fine particles; Step (4): The water in the clean water tank of step (2) is purified by the ultrafiltration system and / or the reverse osmosis system to obtain high-purity water for collection, and the concentrated water produced by the reverse osmosis system is returned to the primary cluster filter for cycle treatment to finally realize solid-liquid separation; The filtration element of the dynamic ceramic membrane filtration system is a ceramic membrane, and 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 surface of the filtration element 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. 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; the concentrated liquid of the primary cluster filter in step (3) is treated in situ by the secondary cluster filter for dehydration and drying until the moisture content of the filter cake layer is less than 30%, and the automatic discharge work is carried out to recover the fine particles. 10.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process of claim 9, wherein, When the particle size of the fine particles in the wastewater is less than 1 μm, the process of claim 1 is selected; when the particle size of the fine particles in the wastewater is not less than 1 μm, the process of claim 9 is selected. 11.The semiconductor wafer cutting-grinding-polishing wastewater resource recovery and utilization process according to claim 1 or 9, characterized in that, The process comprises the following steps:

12. A method for preparing a ceramic membrane for comprehensive recovery of wafer cutting, grinding, and polishing wastewater in a semiconductor process, characterized in that, Step (1): Preparation of support layer Mix micron alumina powder, sintering aid, pore former, dispersant and binder in proportion, ball mill for 4-6 hours to prepare slurry, then spray granulation, dry pressing forming process to prepare support layer blank, dry after dehydration and then sintering treatment; Step (2): Preparation of intermediate layer Mix micron alumina powder, sintering aid, grinding aid, dispersant and binder in proportion, ball mill for 6-8 hours to prepare intermediate layer membrane slurry, then coating, drying and sintering to form membrane intermediate layer; The pore size of the intermediate layer of the ceramic membrane prepared in this step is 0.2-2 um, the roughness Ra is 2.5-10 um, and the Mohs hardness HM is 3-4; Step (3): Preparation of separation layer Mix nano alumina powder, sintering aid, binder and zirconia sol in proportion, stir uniformly to prepare separation layer slurry, then coat, dry and sinter to form membrane separation layer; The pore size of the separation layer of the ceramic membrane prepared in this step is 50-80 nm, the roughness Ra is 0.2-0.4 um, and the Mohs hardness HM is 8-9. The median particle size D(50) of the alumina powder in step (1) is 5-30 um, the median particle size D(50) of the alumina powder in step (2) is 5-10 um, and the median particle size D(50) of the alumina powder in step (3) is 0.1-1 um.

13. The method for preparing ceramic membranes for comprehensive recovery of wafer cutting, grinding, and polishing wastewater in semiconductor processes according to claim 12, characterized in that, ​ 14. The method for preparing ceramic membranes for comprehensive recovery of wafer cutting, grinding, and polishing wastewater in semiconductor processes according to claim 13, characterized in that, The sintering aid in step (1) is titanium oxide (0.5-1.25 wt%) or silicon oxide (2-5 wt%) or magnesium oxide (0.5-2.5 wt%), the pore-forming agent is one or several of starch (3-8 wt%), carbon powder (1-7 wt%), cellulose (1.5-5 wt%), the dispersing agent is one or both 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%).

15. The method for preparing ceramic membranes for comprehensive recovery of wafer cutting, grinding, and polishing wastewater in semiconductor processing according to claim 14, characterized in that, The sintering aid in step (2) is silicon oxide (5-10 wt%), the grinding aid is sodium hexametaphosphate (0.5-1.5 wt%), the dispersing agent is PEG (1-2 wt%), and the binder is a PVA solution with a configured concentration of 2-5% (0.2-0.8 wt%).

16. The method for preparing ceramic membranes for comprehensive recovery of wafer cutting, grinding, and polishing wastewater in semiconductor processing according to claim 15, characterized in that, The sintering aid in step (3) is titanium oxide (10-15 wt%), the binder is a PVA solution with a configured concentration of 5-10% (2-5 wt%), and zirconium oxide sol (2-10 wt%).

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

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