A single crystal diamond polishing fluid for polishing high thermal conductivity aluminum nitride ceramic substrates

Abstract

This invention discloses a single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates, belonging to the field of precision ceramic material processing technology. By using single-crystal diamond instead of polycrystalline diamond, it significantly reduces raw material costs while achieving an equivalent or even higher polishing rate through increased solid content. The polyol lubricant significantly improves the friction state of the polishing interface, reducing micro-pits and scratches. The polished aluminum nitride ceramic substrate exhibits good surface uniformity, meeting the requirements for high-end electronic packaging substrates. In the surface additives prepared by this invention, the conjugated amine groups of the polyaniline segments can efficiently chelate free aluminum ions generated by hydrolysis, directly disrupting the chemical equilibrium of the hydrolysis reaction and preventing the forward hydrolysis. The silanol groups generated by the hydrolysis of the silane bridging agent can form hydrogen bonds and covalent bonds with the hydroxyl groups on the surface of the aluminum nitride substrate, forming a molecular-level dense passivation layer on the substrate surface, fundamentally isolating water molecules from contact with the aluminum nitride matrix.

Description

Technical Field

[0001] This invention belongs to the field of precision ceramic material processing technology, specifically a single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates. Background Technology

[0002] Aluminum nitride ceramic substrates are widely used in third-generation semiconductor packaging and high-power electronic devices due to their high thermal conductivity, good electrical insulation properties, and thermal expansion coefficient that matches that of silicon. With the increasing demands for device integration and reliability, higher requirements are being placed on the surface roughness and flatness of aluminum nitride ceramic substrates, typically requiring a surface roughness Ra of around 10 nm after polishing.

[0003] In existing technologies, the fine polishing process of aluminum nitride ceramic substrates generally uses polycrystalline diamond with a particle size of 100-130nm as the polishing abrasive, and its solid content is generally controlled at about 0.5-1%. This type of polishing fluid has the advantages of high polishing rate and good surface uniformity, but polycrystalline diamond is expensive, which significantly increases the cost of polishing consumables and is not conducive to large-scale industrial application.

[0004] On the other hand, single-crystal diamond has a more regular crystal structure and good single-particle cutting efficiency. However, in practical applications, single-crystal diamond particles have high surface energy and are prone to agglomeration, which can easily cause surface defects such as micro-pits and scratches during the polishing of aluminum nitride ceramics, resulting in a decrease in polishing uniformity and limiting its application in scenarios with high surface quality requirements.

[0005] Therefore, there is an urgent need to develop an aluminum nitride ceramic substrate polishing slurry that uses single-crystal diamond as the main abrasive, combines high polishing rate and excellent surface quality, and has a more cost-effective advantage. Summary of the Invention

[0006] The present invention aims to solve the problem of high cost of existing polycrystalline diamond polishing slurries, and overcome the technical defects of single-crystal diamond polishing slurries, such as easy agglomeration, easy generation of micro-pits and poor surface uniformity during polishing of aluminum nitride ceramic substrates.

[0007] The objective of this invention can be achieved through the following technical solutions: A single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates is prepared by the following steps: Step 1: Utilize the hydroxyl groups on the surface of hydroxylated boron nitride to undergo an esterification reaction with the carboxyl groups of p-aminobenzoic acid under concentrated sulfuric acid catalysis to obtain modified boron nitride.

[0008] Step 2: Using aminotrimethylenephosphonic acid as the doping acid and dispersion medium, ammonium persulfate is used to initiate in-situ oxidative polymerization of aniline monomers on the surface of aminated boron nitride at low temperature, forming a core-shell structure of polyaniline uniformly coated with boron nitride, thus obtaining polyaniline-modified boron nitride powder.

[0009] Step 3: The graphene oxide generated by hydrolysis of 3-(2,3-epoxypropoxy)propyltrimethoxysilane under acidic conditions undergoes dehydration condensation and hydrogen bonding with the hydroxyl and amino groups on the surface of polyaniline-modified boron nitride. The two two-dimensional functional materials are covalently composited using silane as a bridging agent to obtain a surface additive.

[0010] Step 4: Mix single-crystal diamond abrasive with an average particle size of 100-120nm, polyacrylic acid dispersant, polyol lubricant, surface modifier, surface aid, and deionized water, and adjust the pH value to 7-8 to obtain a single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates.

[0011] Furthermore, the ratio of monocrystalline diamond abrasive, polyacrylic acid dispersant, polyol lubricant, surface modifier, surface additive and deionized water is 3-4g: 0.2-0.5g: 1-5g: 0.05-0.5g: 0.05-0.5g: 90-92g.

[0012] Furthermore, the polyacrylic acid dispersant includes any one or a combination of low molecular weight polyacrylic acid homopolymer, polyacrylic acid-maleic anhydride copolymer, and polyacrylic acid polyoxyethylene ether block copolymer.

[0013] Furthermore, polyol lubricants include any one or a combination of ethylene glycol, propylene glycol, glycerin, and polyethylene glycol.

[0014] Furthermore, the surface-modifying agent includes any one or a combination of AEO-7, AEO-9, and polyoxyethylene-polyoxypropylene block copolymers.

[0015] Furthermore, the specific preparation steps for modified boron nitride are as follows: Hydroxylated boron nitride and a 1 mol / L anhydrous ethanol solution of p-aminobenzoic acid were added to a reaction vessel and stirred for 1-2 hours at 20-25℃ and 500-600 r / min. Then concentrated sulfuric acid was added, and the mixture was heated to 50-60℃ and stirred for another 2-3 hours. The mixture was then centrifuged at 8000-9000 r / min for 10-12 minutes. The centrifuged material was collected, washed 2-4 times with anhydrous ethanol, and dried under vacuum at 60-70℃ for 24-26 hours to obtain modified boron nitride.

[0016] Furthermore, the ratio of hydroxylated boron nitride, anhydrous ethanol solution of p-aminobenzoic acid, and concentrated sulfuric acid is 5-5.2 g : 2500-2600 mL : 5-5.2 mL.

[0017] Furthermore, the specific preparation steps for polyaniline-modified boron nitride powder are as follows: Modified boron nitride and a 1 mol / L aminotrimethylenephosphonic acid solution were added to a reaction vessel and stirred for 20-30 min at 20-25℃ and 500-600 r / min. The pH was adjusted to 1 with hydrochloric acid, and the mixture was ultrasonically dispersed for 1-2 h. Then, aniline was added, and stirring was continued for 30-40 min. Ammonium persulfate was then added, and the reaction temperature was controlled at 1-5℃. The reaction was continued for 8-10 h, and the mixture was centrifuged at 8000-9000 r / min for 10-12 min. The centrifuged material was collected, washed 2-4 times with anhydrous ethanol and deionized water, and vacuum dried at 60-70℃ for 24-26 h to obtain polyaniline-modified boron nitride powder.

[0018] Furthermore, the ratio of modified boron nitride, aminotrimethylenephosphonic acid solution, aniline and ammonium persulfate is 4.5-4.7g: 2720-2750mL: 8-8.4g: 1.8-2.5g.

[0019] Furthermore, the specific preparation steps of the surface additive are as follows: 3-(2,3-epoxypropoxy)propyltrimethoxysilane, methanol, and distilled water were added to a reaction vessel and stirred for 1-2 hours at 20-25℃ and 500-600 r / min. The pH was adjusted to 4 with acetic acid, and the reaction was continued for 12-14 hours. Then, graphene oxide and polyaniline-modified boron nitride powder were added, and the mixture was ultrasonically dispersed for 1-2 hours. The mixture was then stirred for 4-5 hours to obtain the surface additive.

[0020] Furthermore, the ratio of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, methanol, distilled water, graphene oxide, and polyaniline-modified boron nitride powder is 5-7g:30-40g:60-70g:0.5-0.8g:0.8-0.9g.

[0021] The beneficial effects of this invention are: 1. This invention uses single-crystal diamond instead of polycrystalline diamond, which significantly reduces the cost of raw materials while achieving an equivalent or even higher polishing rate by increasing the solid content. The polyol lubricant significantly improves the friction state of the polishing interface and reduces micro-pits and scratches. After polishing, the aluminum nitride ceramic substrate has good surface uniformity, and Ra can be stably controlled at 9-13nm, which meets the requirements of high-end electronic packaging substrates.

[0022] 2. This invention utilizes the synergistic effect of polyacrylic acid dispersant and surface modifier to effectively solve the problem of easy agglomeration of single-crystal diamond, significantly improving polishing uniformity. The polyacrylic acid dispersant forms a stable adsorption layer on the particle surface, and its unique comb-like structure provides excellent steric hindrance. By combining the dual effects of electrostatic repulsion and steric hindrance, it effectively inhibits direct contact between nanoparticles, preventing agglomeration and sedimentation, thereby ensuring the long-term particle size stability of the polishing slurry and the uniformity of the polishing process.

[0023] 3. In the surface additives prepared by this invention, the conjugated amine groups of the polyaniline segments can efficiently chelate the free aluminum ions generated by hydrolysis, directly breaking the chemical equilibrium of the hydrolysis reaction and preventing the hydrolysis reaction from proceeding in the forward direction. The silanol groups generated by the hydrolysis of the silane bridging agent can form hydrogen bonds and covalent bonds with the hydroxyl groups on the surface of the aluminum nitride substrate, forming a molecular-level dense passivation layer on the substrate surface, thus isolating water molecules from contact with the aluminum nitride body from the source.

[0024] 4. In the surface additive prepared by this invention, the two-dimensional sheets of graphene oxide and boron nitride form a continuous "nano barrier network" at the polishing interface, which significantly shortens the effective contact time between water molecules and the substrate, and further inhibits hydrolysis from a kinetic perspective. The covalently bonded hybrid structure of the surface additive can open up the gaps between the graphene oxide and boron nitride sheets, avoid interlayer stacking caused by van der Waals forces, and achieve monodispersion of the two-dimensional sheets. The covalently hybridized two-dimensional sheets can form a continuous molecular-level solid lubricating film between the diamond abrasive and the aluminum nitride substrate, avoid hard contact between the abrasive and the substrate, and reduce polishing defects such as scratches, micro-pits, and chipping from the source. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: A single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates is prepared through the following steps: S1: Add 5g of hydroxylated boron nitride and 2500mL of 1mol / L anhydrous ethanol solution of p-aminobenzoic acid to a reaction vessel, stir for 1h at 20℃ and 500r / min, then add 5mL of concentrated sulfuric acid, heat to 50℃, continue stirring for 2h, centrifuge at 8000r / min for 10min, collect the centrifuged material, wash the centrifuged material twice with anhydrous ethanol, and vacuum dry at 60℃ for 24h to obtain modified boron nitride.

[0027] S2: Add 4.5g of modified boron nitride and 2720mL of 1mol / L aminotrimethylenephosphonic acid solution to a reaction vessel. Stir for 20min at 20℃ and 500r / min. Adjust the pH to 1 with hydrochloric acid and sonicate for 1h. Then add 8g of aniline and continue stirring for 30min. Then add 1.8g of ammonium persulfate and control the reaction temperature at 1℃. Continue the reaction for 8h. Centrifuge at 8000r / min for 10min and collect the centrifuged material. Wash the centrifuged material twice with anhydrous ethanol and deionized water. Dry under vacuum at 60℃ for 24h to obtain polyaniline-modified boron nitride powder.

[0028] S3: Add 5g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 30g of methanol and 60g of distilled water to a reaction vessel, stir for 1h at 20℃ and 500r / min, adjust the pH to 4 with acetic acid, continue stirring for 12h, then add 0.5g of graphene oxide and 0.8g of polyaniline-modified boron nitride powder, ultrasonically disperse for 1h, and continue stirring for 4h to obtain the surface additive.

[0029] S4: Mix 3g of single-crystal diamond abrasive with an average particle size of 100nm, 0.2g of polyacrylic acid dispersant, 1g of polyol lubricant, 0.05g of surface modifier, 0.05g of surface additive, and 90g of deionized water to obtain a single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates.

[0030] Example 2: A single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates is prepared through the following steps: S1: 5.1 g of hydroxylated boron nitride and 2550 mL of 1 mol / L anhydrous ethanol solution of p-aminobenzoic acid were added to a reaction vessel and stirred at 22.5 °C and 550 r / min for 1.5 h. Then, 5.1 mL of concentrated sulfuric acid was added, the mixture was heated to 55 °C, and stirring was continued for 2.5 h. The mixture was centrifuged at 8500 r / min for 11 min, and the centrifuged material was collected. The centrifuged material was washed three times with anhydrous ethanol and dried under vacuum at 65 °C for 25 h to obtain modified boron nitride.

[0031] S2: 4.6 g of modified boron nitride and 2735 mL of 1 mol / L aminotrimethylenephosphonic acid solution were added to a reaction vessel and stirred for 25 min at 22.5 °C and 550 r / min. The pH was adjusted to 1 with hydrochloric acid and ultrasonically dispersed for 1.5 h. Then 8.2 g of aniline was added and stirring was continued for 35 min. Then 2.15 g of ammonium persulfate was added and the reaction temperature was controlled at 3 °C. The reaction was continued for 9 h. The mixture was centrifuged at 8500 r / min for 11 min and the centrifuged material was collected. The centrifuged material was washed three times with anhydrous ethanol and deionized water and dried under vacuum at 65 °C for 25 h to obtain polyaniline-modified boron nitride powder.

[0032] S3: Add 6g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 35g of methanol and 65g of distilled water to a reaction vessel, stir for 1.5h at 22.5℃ and 550r / min, adjust the pH to 4 with acetic acid, and continue stirring for 13h. Then add 0.65g of graphene oxide and 0.85g of polyaniline-modified boron nitride powder, disperse ultrasonically for 1.5h, and continue stirring for 4.5h to obtain the surface additive.

[0033] S4: Mix 3.5g of single-crystal diamond abrasive with an average particle size of 110nm, 0.35g of polyacrylic acid dispersant, 3g of polyol lubricant, 0.275g of surface modifier, 0.275g of surface additive, and 91g of deionized water to obtain a single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates.

[0034] Example 3: A single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates is prepared through the following steps: SS1: 5.2 g of hydroxylated boron nitride and 2600 mL of 1 mol / L anhydrous ethanol solution of p-aminobenzoic acid were added to a reaction vessel and stirred at 25 °C and 600 r / min for 2 h. Then, 5.2 mL of concentrated sulfuric acid was added, the mixture was heated to 60 °C, and stirring was continued for 3 h. The mixture was centrifuged at 9000 r / min for 12 min, and the centrifuged material was collected. The centrifuged material was washed four times with anhydrous ethanol and dried under vacuum at 70 °C for 26 h to obtain modified boron nitride.

[0035] S2: 4.7 g of modified boron nitride and 2750 mL of 1 mol / L aminotrimethylenephosphonic acid solution were added to a reaction vessel and stirred at 25 °C and 600 r / min for 30 min. The pH was adjusted to 1 with hydrochloric acid and ultrasonically dispersed for 2 h. Then 8.4 g of aniline was added and stirring was continued for 40 min. Then 2.5 g of ammonium persulfate was added and the reaction temperature was controlled at 5 °C. The reaction was continued for 10 h. The mixture was centrifuged at 9000 r / min for 12 min and the centrifuged material was collected. The centrifuged material was washed four times with anhydrous ethanol and deionized water and vacuum dried at 70 °C for 26 h to obtain polyaniline-modified boron nitride powder.

[0036] S3: Add 7g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 40g of methanol and 70g of distilled water to a reaction vessel, stir for 2h at 25℃ and 600r / min, adjust the pH to 4 with acetic acid, continue stirring for 14h, then add 0.8g of graphene oxide and 0.9g of polyaniline-modified boron nitride powder, ultrasonically disperse for 2h, and continue stirring for 5h to obtain the surface additive.

[0037] S4: Mix 4g of single-crystal diamond abrasive with an average particle size of 120nm, 0.5g of polyacrylic acid dispersant, 5g of polyol lubricant, 0.5g of surface modifier, 0.5g of surface additive, and 92g of deionized water to obtain a single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates.

[0038] Comparative Example 1: Based on Example 3, the surface additive in step S4 was replaced with the modified boron nitride prepared in step S1.

[0039] Comparative Example 2: Based on Example 3, the surface additive in step S4 was replaced with the polyaniline-modified boron nitride powder prepared in step S2.

[0040] Performance tests were conducted on Examples 1-3 and Comparative Examples 1-2, and the results are shown in Table 1: Table 1 project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 (100) Crystal plane (nm) 11.062 10.064 9.068 15.002 14.012 (110) Crystal plane (nm) 10.596 10.571 9.564 16.623 17.618 (111) Crystal plane (nm) 11.245 10.212 10.186 18.298 16.282 As shown in Table 1, Comparative Example 1 only grafted amino groups onto the boron nitride surface. It lacked the aluminum ion chelating ability of polyaniline conjugated amino groups, the covalent passivation layer of silane hydrolysis products, and the two-dimensional nano-barrier network of graphene oxide-boron nitride. Therefore, it could not block the AlN hydrolysis reaction from the three dimensions of chemical equilibrium, interfacial isolation, and kinetics. After polishing, a large amount of aluminum hydroxide corrosion layer was formed on the substrate surface, which could not meet the requirements for high-end electronic packaging substrates.

[0041] Polyaniline-modified boron nitride powder can only achieve limited aluminum ion chelation through the conjugated amine groups of polyaniline. It lacks the covalent passivation layer formed by silane hydrolysis products and AlN substrate, and also lacks the nano-barrier network formed by graphene oxide-boron nitride two-dimensional sheets. It cannot fundamentally isolate the contact between water molecules and AlN bulk, resulting in a decrease in hydrolysis inhibition effect. Even after polishing, the substrate still exhibits significant hydrolytic corrosion.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates, characterized in that, Prepared by the following steps: Step 1: Utilizing the hydroxyl groups on the surface of hydroxylated boron nitride, an esterification reaction is carried out with the carboxyl groups of p-aminobenzoic acid under the catalysis of concentrated sulfuric acid to obtain modified boron nitride; Step 2: Using aminotrimethylenephosphonic acid as the doping acid and dispersion medium, ammonium persulfate is used to initiate in-situ oxidative polymerization of aniline monomers on the surface of aminated boron nitride at low temperature, forming a core-shell structure of polyaniline uniformly coated with boron nitride, and obtaining polyaniline modified boron nitride powder. Step 3: The graphene oxide generated by hydrolysis of 3-(2,3-epoxypropoxy)propyltrimethoxysilane under acidic conditions undergoes dehydration condensation and hydrogen bonding with the hydroxyl and amino groups on the surface of polyaniline-modified boron nitride. The two two-dimensional functional materials are covalently composited using silane as a bridging agent to obtain a surface additive. Step 4: Mix single-crystal diamond abrasive with an average particle size of 100-120nm, polyacrylic acid dispersant, polyol lubricant, surface modifier, surface aid, and deionized water, and adjust the pH value to 7-8 to obtain a single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates.

2. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 1, characterized in that, The ratio of the amount of the single-crystal diamond abrasive, polyacrylic acid dispersant, polyol lubricant, surface modifier, surface additive and deionized water is 3-4g: 0.2-0.5g: 1-5g: 0.05-0.5g: 0.05-0.5g: 90-92g.

3. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 1, characterized in that, The polyacrylic acid dispersant includes any one or a combination of low molecular weight polyacrylic acid homopolymer, polyacrylic acid-maleic anhydride copolymer, and polyacrylic acid polyoxyethylene ether block copolymer.

4. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 1, characterized in that, The polyol lubricant includes any one or a combination of ethylene glycol, propylene glycol, glycerin, and polyethylene glycol.

5. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 1, characterized in that, The surface-modifying agent includes any one or a combination of AEO-7, AEO-9, and polyoxyethylene-polyoxypropylene block copolymer.

6. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 1, characterized in that, The specific preparation steps for the modified boron nitride are as follows: Hydroxylated boron nitride and a 1 mol / L anhydrous ethanol solution of p-aminobenzoic acid were added to a reaction vessel and stirred for 1-2 hours at 20-25℃ and 500-600 r / min. Then concentrated sulfuric acid was added, and the mixture was heated to 50-60℃ and stirred for another 2-3 hours. The mixture was then centrifuged at 8000-9000 r / min for 10-12 minutes. The centrifuged material was collected, washed 2-4 times with anhydrous ethanol, and dried under vacuum at 60-70℃ for 24-26 hours to obtain modified boron nitride. The ratio of hydroxylated boron nitride, anhydrous ethanol solution of p-aminobenzoic acid, and concentrated sulfuric acid is 5-5.2 g: 2500-2600 mL: 5-5.2 mL.

7. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 1, characterized in that, The specific preparation steps of the polyaniline-modified boron nitride powder are as follows: Modified boron nitride and a 1 mol / L aminotrimethylenephosphonic acid solution were added to a reaction vessel and stirred for 20-30 min at 20-25℃ and 500-600 r / min. The pH was adjusted to 1 with hydrochloric acid, and the mixture was ultrasonically dispersed for 1-2 h. Then, aniline was added, and stirring was continued for 30-40 min. Ammonium persulfate was then added, and the reaction temperature was controlled at 1-5℃. The reaction was continued for 8-10 h, and the mixture was centrifuged at 8000-9000 r / min for 10-12 min. The centrifuged material was collected, washed 2-4 times with anhydrous ethanol and deionized water, and vacuum dried at 60-70℃ for 24-26 h to obtain polyaniline-modified boron nitride powder.

8. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 1, characterized in that, The ratio of modified boron nitride, aminotrimethylenephosphonic acid solution, aniline and ammonium persulfate is 4.5-4.7g: 2720-2750mL: 8-8.4g: 1.8-2.5g.

9. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 1, characterized in that, The specific preparation steps for the surface additive are as follows: 3-(2,3-epoxypropoxy)propyltrimethoxysilane, methanol, and distilled water were added to a reaction vessel and stirred for 1-2 hours at 20-25℃ and 500-600 r / min. The pH was adjusted to 4 with acetic acid, and the reaction was continued for 12-14 hours. Then, graphene oxide and polyaniline-modified boron nitride powder were added, and the mixture was ultrasonically dispersed for 1-2 hours. The mixture was then stirred for 4-5 hours to obtain the surface additive.

10. The single-crystal diamond polishing slurry for polishing high thermal conductivity aluminum nitride ceramic substrates according to claim 9, characterized in that, The ratio of the amounts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, methanol, distilled water, graphene oxide, and polyaniline-modified boron nitride powder is 5-7g:30-40g:60-70g:0.5-0.8g:0.8-0.9g.