Preparation method and application of core-shell structure composite abrasive with magnetic core

Abstract

The invention discloses a preparation method and application of a core-shell structure composite abrasive with a magnetic core, and belongs to the technical field of semiconductor manufacturing and ultra-precision machining.The preparation method comprises the following steps that S1, FeCl3. 6H2O and FeCl2. 4H2O are weighed, deionized water and ammonia water are added for a reaction, and magnetic separation, washing and drying are conducted; s2, carrying out ultrasonic dispersion on a product obtained in the step S1, adding ethyl silicate and ammonia water to react, centrifuging, washing and drying; s3, dispersing a product obtained in the step S2 in deionized water, adding a nano metal oxide for reaction, and performing centrifugal washing and calcination; and S4, dispersing the product obtained in the step S3 in absolute ethyl alcohol, adding KH550 and a high-molecular polymer for reaction, centrifuging, washing and drying to obtain the abrasive material. The invention provides a composite abrasive which can be stably and circularly used for 8-10 times, the single use cost is only 15-20% of that of a traditional abrasive, and the process cost is reduced by more than 60%.

Description

Technical Field

[0001] This invention relates to the fields of semiconductor manufacturing technology and ultra-precision machining technology, and more specifically, to a method for preparing and applying a core-shell composite abrasive with a magnetic core. Background Technology

[0002] As semiconductor manufacturing processes advance to 3nm and below, the application frequency of chemical mechanical polishing (CMP) has increased significantly, leading to a substantial rise in abrasive consumption. Related data shows that a single 12-inch wafer production line consumes over ten million yuan worth of cerium oxide abrasive annually, and this abrasive is directly discharged with the waste liquid after use, without effective recycling. Existing recycling technologies mainly include precipitation, membrane filtration, and centrifugation, but all have significant limitations, making it difficult to achieve efficient and non-destructive abrasive recovery. Against this backdrop, the prominent technical challenges facing the semiconductor CMP field are as follows:

[0003] (1) Waste of resources and high cost: Rare earth abrasives such as nano-grade cerium oxide are scarce resources and expensive (the market price of 99.9% pure nano-CeO2 is about RMB 500-800 / kg). At present, the abrasives in the CMP process are all used "once" and discharged with the waste liquid, resulting in high wafer manufacturing costs and serious waste of resources.

[0004] (2) High environmental protection pressure: CMP waste liquid contains a large number of nano-sized solid suspended matter (abrasive particles), with a concentration of 5-10 g / L. Traditional precipitation methods require the addition of a large amount of flocculant, which can easily cause secondary pollution. Membrane filtration has membrane clogging problems, resulting in low treatment efficiency and high cost. Centrifugation has high energy consumption and it is difficult to achieve complete separation of abrasive particles, which leads to a significant increase in the difficulty and cost of wastewater treatment.

[0005] (3) Risk of metal contamination: Some studies have attempted to introduce magnetic particles (such as Fe3O4 and CoFe2O4) into the abrasive to achieve magnetic recovery. However, traditional magnetic particles are prone to dissolution in the acidic or alkaline environment (pH=2-11) of CMP polishing fluid, releasing metal ions such as Fe and Co. These metal ions will be adsorbed on the wafer surface, causing the device's electrical performance to fail and seriously affecting the product yield.

[0006] (4) Abrasive performance degradation after recycling: Existing recycling technology is prone to agglomeration and morphological damage of abrasive particles. The abrasive after recycling has poor dispersion, which can easily cause scratches on the wafer surface during polishing. In addition, the material removal rate (MRR) drops significantly, which cannot meet the requirements for secondary use.

[0007] The core reason for the above problems is that there is a lack of abrasive structures with a synergistic design of "high-efficiency magnetic response + anti-metal contamination + high polishing performance". The stability and adaptability of existing magnetic abrasives are insufficient, and the supporting recycling process has failed to solve the problems of agglomeration and performance degradation during the abrasive recycling process. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing and applying a core-shell composite abrasive with a magnetic core.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for preparing a core-shell composite abrasive with a magnetic core includes the following steps:

[0011] S1. Weigh FeCl3·6H2O and FeCl2·4H2O, add deionized water, stir until dissolved under nitrogen protection, add ammonia to adjust the pH value, stir the reaction to generate Fe3O4 precipitate, magnetically separate, wash, dry to obtain magnetic nanoparticles.

[0012] S2. Magnetic nanoparticles are dispersed in an ethanol-water mixed solution, ultrasonically dispersed, ethyl silicate and ammonia are added, stirred and reacted, centrifuged, washed and dried to obtain composite particles.

[0013] S3. Disperse the composite particles in deionized water, add nano-metal oxides, stir until dissolved, adjust the pH to alkaline, react to obtain a precipitate, centrifuge, wash, dry, and calcine to obtain core-shell particles.

[0014] S4. Disperse the core-shell particles in anhydrous ethanol, add KH550 and polymer, stir and react, centrifuge to separate the initial product after stirring, wash and dry to obtain a core-shell composite abrasive with a magnetic core.

[0015] Further, in step S1, the molar ratio of FeCl3·6H2O and FeCl2·4H2O is 2:1, and the mixture is dried at 50-70℃ for 6-10 hours.

[0016] Further, in step S2, the reaction is stirred at room temperature for 4-8 hours. The ratio of magnetic nanoparticles, ethanol-water mixed solution, ethyl silicate and ammonia is (3-7) g: (100-200) mL: (1-4) mL: (3-7) mL. The mass fraction of ammonia is 25%. The ethanol-water mixed solution is prepared according to the volume ratio of ethanol to water of 3:1.

[0017] Further, in step S3, the ratio of composite particles, deionized water and nano-metal oxide is (1-5) g: (50-150) mL: (8-16) g, the nano-metal oxide is Ce(NO3)3·6H2O or AlCl3·6H2O, the pH value is adjusted to 9.0 with NaOH solution, the reaction is stirred at 50-70℃ for 1-3 h, and calcined at 500-600℃.

[0018] Further, in step S4, the reaction is stirred at 50-90℃ for 2-6 hours. The ratio of the amount of core-shell particles, anhydrous ethanol, KH550 and polymer is (1-3) g: (50-110) mL: (0.3-1.1) g: (0.5-1.1) g. The polymer is polyethylene glycol or polyacrylic acid.

[0019] An application of a core-shell composite abrasive with a magnetic core, wherein the core-shell composite abrasive with a magnetic core is used for silicon wafer polishing.

[0020] Furthermore, it includes the following steps:

[0021] (a) Preparation of polishing solution: Add composite abrasive to deionized water, add polyacrylic acid and H2O2 solution, and adjust the pH value to 9.0-11.0 with KOH solution;

[0022] (b) Polishing process: The silicon wafer to be polished is added to the polishing solution and polished to obtain the polished silicon wafer.

[0023] Further, in step (a), based on 100% of the total mass of the polishing slurry, the components of the polishing slurry are: 3-7 wt% composite abrasive, 0.1-0.3 wt% polyacrylic acid, 0.05-0.15 wt% H2O2, and the remainder is deionized water.

[0024] In summary, the present invention has the following beneficial effects:

[0025] (1) Significantly reduce process costs: The abrasive can be stably recycled 8-10 times, and the cost per use is only 15-20% of that of traditional disposable abrasives, reducing the cost of CMP process per wafer by more than 60%;

[0026] (2) Outstanding environmental benefits: Abrasive recovery rate ≥99%, significantly reducing the content of suspended solids in waste liquid (from 5-10g / L to below 0.1g / L), reducing the difficulty and cost of wastewater treatment, and reducing resource waste;

[0027] (3) Excellent anti-pollution performance: The dense SiO2 barrier layer completely isolates the magnetic core from the external environment, effectively preventing the precipitation of Fe ions, and the metal contamination concentration on the wafer surface is far lower than the industry standard.

[0028] (4) Stable polishing performance: The superparamagnetic core ensures that the abrasive maintains good monodispersity in a magnetic field-free environment after recycling. Even after multiple cycles, it can still maintain a high removal rate and low surface roughness, without generating additional scratches.

[0029] (5) Strong process adaptability: The preparation process is simple and controllable, and it can be mass-produced. The abrasive is compatible with existing CMP equipment and polishing fluid system, and can directly replace traditional abrasives without additional equipment modification. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the abrasive prepared in Example 1;

[0031] Figure 2 SEM image of the abrasive prepared in Example 1;

[0032] Figure 3 TEM image of the abrasive prepared in Example 1. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] A method for preparing a core-shell composite abrasive with a magnetic core:

[0035] S1. Mix FeCl3·6H2O and FeCl2·4H2O, add deionized water, and stir at 50℃ under nitrogen protection until dissolved. The molar ratio of FeCl3·6H2O to FeCl2·4H2O is 2:1. Add ammonia water dropwise to adjust the pH value, stir the reaction, and generate Fe3O4 precipitate. Separate magnetically, wash, and dry at 50-70℃ for 6-10h to obtain magnetic nanoparticles.

[0036] S2. Disperse the magnetic nanoparticles in an ethanol-water mixed solution and ultrasonically disperse for 20-40 min. Add ethyl silicate and ammonia and stir at room temperature for 4-8 h. The ratio of magnetic nanoparticles, ethanol-water mixed solution, ethyl silicate and ammonia is (3-7) g: (100-200) mL: (1-4) mL: (3-7) mL. The mass fraction of ammonia is 25%. The ethanol-water mixed solution is prepared according to the volume ratio of ethanol to water of 3:1. Centrifuge, wash and dry to obtain composite particles.

[0037] S3. Disperse the composite particles in deionized water, add nano-metal oxide, and stir until dissolved. The ratio of composite particles, deionized water and nano-metal oxide is (1-5) g: (50-150) mL: (8-16) g. The nano-metal oxide is Ce(NO3)3·6H2O or AlCl3·6H2O. Adjust the pH value to 9.0 with NaOH solution. Stir the reaction at 50-70℃ for 1-3 h. After centrifugation, wash and dry the product. Calcine it at 500-600℃ in air for 3-5 h to obtain core-shell particles.

[0038] S4. Disperse the core-shell particles in anhydrous ethanol, add KH550, add polymer, and stir at 50-90℃ for 2-6 hours. The ratio of core-shell particles, anhydrous ethanol, KH550 and polymer is (1-3) g: (50-110) mL: (0.3-1.1) g: (0.5-1.1) g. The polymer is polyethylene glycol or polyacrylic acid. After centrifugation, wash with anhydrous ethanol and dry at 50-70℃ for 3-7 hours to obtain a core-shell composite abrasive with a magnetic core.

[0039] Application of a core-shell composite abrasive with a magnetic core:

[0040] The core-shell composite abrasive with a magnetic core is used for silicon wafer polishing, including the following steps:

[0041] (a) Preparation of polishing solution: Add composite abrasive to deionized water, add polyacrylic acid and H2O2 solution, adjust the pH value to 9.0-11.0 with KOH solution, and stir at 400r / min for 3h at room temperature;

[0042] Based on the total mass of the polishing slurry (100%), the components of the polishing slurry are: 3-7 wt% composite abrasive, 0.1-0.3 wt% polyacrylic acid, 0.05-0.15 wt% H2O2, and the remainder is deionized water.

[0043] (b) Polishing treatment: Take one silicon wafer to be polished, add 15mL of polishing liquid, place it in a polishing machine for polishing treatment for 1 hour, and clean it to obtain the polished silicon wafer.

[0044] Example 1

[0045] Preparation method of core-shell composite abrasive with magnetic core:

[0046] (1) Preparation of superparamagnetic Fe3O4 core (coprecipitation method):

[0047] molar ratio Fe 3+ :Fe 2+=2:1, weigh 10g FeCl3·6H2O and 4.3g FeCl2·4H2O, add 200mL deionized water, and stir at 50℃ under nitrogen protection until completely dissolved;

[0048] The pH value was adjusted to 10.0 by rapidly adding 25% ammonia water, and the mixture was stirred at a constant temperature for 30 min to generate a black Fe3O4 precipitate. The precipitate was then magnetically separated, washed with deionized water until neutral, and vacuum dried at 60℃ for 8 h to obtain superparamagnetic Fe3O4 nanoparticles.

[0049] (2) Dense SiO2 barrier layer coating (Stöber method):

[0050] 5g of superparamagnetic Fe3O4 nanoparticles were dispersed in 150mL of ethanol-water mixed solution (volume ratio 3:1) and ultrasonically dispersed for 30min.

[0051] Add 3 mL of tetraethyl orthosilicate (TEOS) and 5 mL of ammonia water (25% by mass), stir at room temperature for 6 h, and form a dense SiO2 layer on the surface of superparamagnetic Fe3O4 nanoparticles through sol-gel reaction;

[0052] Centrifugation (8000 rpm, 15 min), washing three times with anhydrous ethanol, and drying at 50 °C for 6 h yielded Fe3O4@SiO2 composite particles.

[0053] (3) CeO2 functional layer loading (in-situ deposition-calcination method):

[0054] Disperse 3g of Fe3O4@SiO2 composite particles in 100mL of deionized water, add 12g of Ce(NO3)3·6H2O, and stir until dissolved;

[0055] The pH value was adjusted to 9.0 using 0.1 mol / L NaOH solution, and the mixture was stirred at 60℃ for 2 hours to allow Ce(OH)3 to be uniformly deposited on the surface of Fe3O4@SiO2 composite particles.

[0056] After centrifugation, the particles were washed three times, dried at 110℃ for 12 hours, and then calcined at 550℃ for 4 hours in air (heating rate 5℃ / min) to convert Ce(OH)3 into CeO2, yielding Fe3O4@SiO2@CeO2 core-shell particles.

[0057] (4) Surface modification (grafting PEG):

[0058] Take 2g of core-shell particles and disperse them in 80mL of anhydrous ethanol. Add 0.5g of silane coupling agent KH550 and 0.8g of polyethylene glycol (PEG, molecular weight 2000). Stir at 70℃ for 4h.

[0059] After centrifugation, the abrasive was washed twice with anhydrous ethanol and dried at 60°C for 5 hours to obtain a core-shell composite abrasive with a magnetic core. A schematic diagram of the abrasive structure prepared in Example 1 is shown below. Figure 1 As shown, the SEM image of the abrasive prepared in Example 1 is as follows. Figure 2 As shown, the TEM image of the abrasive prepared in Example 1 is as follows. Figure 3 As shown.

[0060] Applications of core-shell composite abrasives with magnetic cores:

[0061] The core-shell composite abrasive with a magnetic core is used for silicon wafer polishing, including the following steps:

[0062] (a) Preparation of polishing solution: The core-shell composite abrasive with a magnetic core was added to deionized water, along with polyacrylic acid and hydrogen peroxide. The pH was adjusted to 10 with KOH, and the mixture was stirred at 400 r / min for 3 h to obtain the polishing solution. Based on the total mass of the polishing solution (100%), the components were: 5 wt% composite abrasive, 0.2 wt% polyacrylic acid (molecular weight 3000), 0.1 wt% H2O2, and the remainder being deionized water.

[0063] (b) Polishing treatment: Take one silicon wafer to be polished, add 15mL of polishing liquid, and polish for 1 hour;

[0064] Polishing process: pressure 2.0psi, speed 90rpm / 80rpm (grinding disc / sample tray), slurry supply 10mL / min.

[0065] (c) Recycling:

[0066] The polished composite abrasive was adsorbed in a 0.5T magnetic field for 1 minute, then ultrasonically removed from the magnetic field for 3 minutes, and the composite abrasive was collected for reuse.

[0067] Example 2

[0068] The steps for preparing and polishing the abrasive are the same as those in Example 1, except that in step (2), the amount of TEOS added is changed to 1.5 mL and the thickness of the SiO2 barrier layer is controlled to 5 nm.

[0069] Example 3

[0070] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that in step (2), the amount of TEOS added is changed to 4.5 mL and the thickness of the SiO2 barrier layer is controlled to 10 nm.

[0071] Example 4

[0072] The steps are the same as those in Example 1 for abrasive preparation and polishing application, except that in step (c), the magnetic field strength is increased to 1.0T during recycling and the adsorption time is shortened to 30s.

[0073] Example 5

[0074] The steps for preparing and polishing the abrasive in Example 1 are the same, except that in step (3), Ce(NO3)3·6H2O is replaced with 10g of AlCl3·6H2O, and in step (4), polyethylene glycol is replaced with 0.8g of polyacrylic acid (PAA, molecular weight 4000).

[0075] Comparative Example 1

[0076] The steps are the same as those in Example 1 for abrasive polishing, except that in step (a), the abrasive is commercial nano CeO2 (purchased from Hangzhou Jiupeng New Materials Co., Ltd., item number: CY-Ce02), and the abrasive solid content of the polishing slurry is 5%; step (c) is omitted, and the abrasive is not recycled.

[0077] Comparative Example 2

[0078] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that step (2) is omitted and step (3) is directly performed after step (1).

[0079] Comparative Example 3

[0080] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that step (4) is omitted and step (a) is directly performed after step (3).

[0081] Comparative Example 4

[0082] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that in step (1), FeCl3·6H2O and FeCl2·4H2O are replaced with 3.8g of CoCl2·6H2O and 10g of FeCl3·6H2O (molar ratio Co:Fe=1:2).

[0083] Comparative Example 5

[0084] The steps are the same as those in Example 1 for abrasive preparation and polishing application, except that in step (c), instead of magnetic recovery, a ceramic membrane filter (50 nm pore size) is used to recover the abrasive.

[0085] Performance test results and comparative analysis

[0086] The following equipment and methods were used to test the performance:

[0087] Polishing performance: AFM tests Ra and RMS, and electronic balance is used to measure mass difference to calculate material removal rate (MRR).

[0088] Recovery performance: Recovery rate was measured by gravimetric method, and particle size distribution after recovery was tested by DLS.

[0089] Contamination test: The Fe ion concentration on the wafer surface was detected by ICP-MS according to GB / T 39145-2020 "Determination of Metal Element Content on Silicon Wafer Surface by Inductively Coupled Plasma Mass Spectrometry";

[0090] Stability: The settling rate of the polishing slurry was tested after standing for 72 hours.

[0091] The abrasive in Example 1 had a Zeta potential of -35mV and a D50 of 128nm, which was very similar to the initial state (D50 = 122nm), with no obvious agglomeration. Other test results are shown in Tables 1 and 2 below:

[0092] Table 1

[0093]

[0094] Table 2

[0095]

[0096] Results analysis:

[0097] (1) The anti-pollution advantages of core-shell structure + dense barrier layer

[0098] The Fe ion concentration in Example 1 (containing a SiO2 barrier layer) was only 3.2 × 10⁻⁶. 9 atoms / cm 2 This is significantly lower than that of Comparative Example 2 (without a barrier layer, 8.7 × 10⁻⁶). 10 atoms / cm 2 It meets the pollution threshold requirements of the semiconductor industry.

[0099] Reason: The dense SiO2 barrier layer (8nm thick) forms a physical barrier, completely isolating the Fe3O4 core from the acid-base polishing solution and preventing metal ion penetration; Example 3 (10nm thick barrier layer) has an even lower ion concentration (2.5×10). 9 atoms / cm 2 This further verifies the anti-pollution effect of the barrier layer.

[0100] (2) Surface modification improves cycle stability

[0101] In Example 1 (PEG modified), the MRR decreased by only 8.3% (325→298nm / min) after 10 cycles, and the Ra increased only to 0.23nm; while in Comparative Example 3 (unmodified), the MRR decreased by 40.3% (305→182nm / min) after 10 cycles, the Ra increased to 0.41nm, and a large number of scratches appeared.

[0102] Reason: The PEG molecular chain forms a three-dimensional protective layer on the surface of the abrasive, with an absolute value of zeta potential ≥30mV, which effectively inhibits particle agglomeration and ensures dispersion and grinding uniformity during repeated use.

[0103] (3) High efficiency and low cost of magnetic recovery

[0104] Example 1 achieved a recovery efficiency of 99.5%, with a single recovery time of only 1 minute, and the cost dropped to 28 yuan / L after 10 cycles; Comparative Example 5 (membrane filtration) had a recovery efficiency of only 82%, a recovery time of 30 minutes, and a cost of 35 yuan / L; Comparative Example 1 (disposable) had a cost as high as 146 yuan / L.

[0105] Example 4 (1.0T magnetic field) shows that the recovery time is shortened to 30s while the efficiency is still 99.6%, proving that magnetic recovery is highly efficient and convenient, and significantly reduces process costs and environmental pressure.

[0106] (4) The functional layer can be flexibly adapted to different polishing requirements.

[0107] Example 5 (Al2O3 functional layer) has an initial MRR of 298 nm / min and Ra of 0.20 nm. After 10 recycling cycles, its performance degradation rate is comparable to that of Example 1, making it suitable for polishing scenarios with higher hardness requirements.

[0108] Comparing Example 1 (CeO2 functional layer) with Example 5, it is demonstrated that the core-shell structure of the present invention can flexibly replace the functional layer material, adapt to different CMP process requirements, and has strong compatibility.

[0109] (5) Optimization advantages of magnetic core selection

[0110] Example 1 (Fe3O4 core) cost 28 yuan / L and its performance was stable after 10 recycling cycles; Comparative Example 4 (CoFe2O4 core) cost 85 yuan / L. Although the performance was similar, the cost was significantly higher and the Co ions were more toxic, posing a greater environmental risk.

[0111] This demonstrates that Fe3O4 is the optimal core selection that combines magnetic responsiveness, low cost, and low pollution, further highlighting the innovative raw material selection of this invention.

[0112] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a core-shell composite abrasive with a magnetic core, characterized in that, Includes the following steps: S1. Mix FeCl3·6H2O and FeCl2·4H2O, add deionized water, stir until dissolved under nitrogen protection, add ammonia to adjust the pH value, stir the reaction to generate Fe3O4 precipitate, magnetically separate, wash, dry to obtain magnetic nanoparticles. S2. Magnetic nanoparticles are dispersed in an ethanol-water mixed solution, ultrasonically dispersed, ethyl silicate and ammonia are added, stirred and reacted, centrifuged, washed and dried to obtain composite particles; S3. Disperse the composite particles in deionized water, add nano-metal oxides, stir until dissolved, adjust the pH to alkaline, react to obtain a precipitate, centrifuge, wash, dry, and calcine to obtain core-shell particles. S4. Disperse the core-shell particles in anhydrous ethanol, add KH550 and polymer, stir and react, centrifuge to separate the initial product after stirring, wash and dry to obtain a core-shell composite abrasive with a magnetic core.

2. The method for preparing a core-shell composite abrasive with a magnetic core according to claim 1, characterized in that, In step S1, the molar ratio of FeCl3·6H2O and FeCl2·4H2O is 2:1, and the mixture is dried at 50-70℃ for 6-10 hours.

3. The method for preparing a core-shell composite abrasive with a magnetic core according to claim 1, characterized in that, In step S2, the reaction is stirred at room temperature for 4-8 hours. The ratio of magnetic nanoparticles, ethanol-water mixed solution, ethyl silicate and ammonia is (3-7) g: (100-200) mL: (1-4) mL: (3-7) mL. The mass fraction of ammonia is 25%. The ethanol-water mixed solution is prepared according to the volume ratio of ethanol to water of 3:

1.

4. The method for preparing a core-shell composite abrasive with a magnetic core according to claim 1, characterized in that, In step S3, the ratio of composite particles, deionized water and nano metal oxide is (1-5) g: (50-150) mL: (8-16) g. The nano metal oxide is Ce(NO3)3·6H2O or AlCl3·6H2O. The pH value is adjusted to 9.0 with NaOH solution. The reaction is stirred at 50-70℃ for 1-3 hours and then calcined at 500-600℃.

5. The method for preparing a core-shell composite abrasive with a magnetic core according to claim 1, characterized in that, In step S4, the reaction is stirred at 50-90℃ for 2-6 hours. The ratio of the amount of core-shell particles, anhydrous ethanol, KH550 and polymer is (1-3) g: (50-110) mL: (0.3-1.1) g: (0.5-1.1) g. The polymer is polyethylene glycol or polyacrylic acid.

6. An application of a core-shell structured composite abrasive with a magnetic core prepared by the method according to any one of claims 1-5, characterized in that, The core-shell composite abrasive with a magnetic core is used for polishing silicon wafers.

7. The application of the core-shell structured composite abrasive with a magnetic core according to claim 6, characterized in that, Includes the following steps: (a) Preparation of polishing solution: Add composite abrasive to deionized water, add polyacrylic acid and H2O2 solution, and adjust the pH value to 9.0-11.0 with KOH solution; (b) Polishing process: The silicon wafer to be polished is added to the polishing solution and polished to obtain the polished silicon wafer.

8. The application of the core-shell structured composite abrasive with a magnetic core according to claim 7, characterized in that, In step (a), based on the total mass of the polishing slurry (100%), the components of the polishing slurry are: 3-7 wt% composite abrasive, 0.1-0.3 wt% polyacrylic acid, 0.05-0.15 wt% H2O2, and the remainder is deionized water.

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