Wafer abrasives, polishing liquids, and methods of making and using the same

Abstract

The application provides a wafer abrasive, a polishing liquid and a preparation method and application thereof. The wafer abrasive has a core-shell structure, and the core-shell structure at least comprises an inner core layer and an outer shell layer coated on the surface of the inner core layer. The material of the inner core layer is silicon carbide powder; and the material of the outer shell layer is hyperbranched polycarbosilane with a hydrophilic group. The abrasive is designed as a core-shell structure through organic modification treatment, and the polycarbosilane shell layer with the hydrophilic group effectively improves the abrasive adhesion effect and the abrasive adhesion and removal capacity. The high-strength silicon carbide powder inner core layer is used to maintain the polishing removal amount. The polishing liquid can produce a strong chemical reaction in a basic environment during use, realizes self-revival of the abrasive and brings a circulating chemical removal capacity. The wafer abrasive and the polishing liquid provided by the application greatly save the abrasive consumption and the manufacturing cost.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a wafer abrasive, polishing slurry, preparation method thereof, and application thereof. Background Technology

[0002] Chemical mechanical polishing (CMP) is an effective method for achieving wafer planarization in semiconductor chip manufacturing and a key step in wafer fabrication. Its role is to reduce surface roughness on the wafer. Polishing slurry is a key consumable in CMP technology, accounting for 49% of the value of CMP consumables. The quality of the abrasive in the polishing slurry directly affects the polishing effect, and is therefore crucial for improving wafer manufacturing quality.

[0003] As the hardness and size of the abrasive grains in the polishing slurry increase, the workpiece removal rate increases, but at the same time, scratches increase, and the surface quality of the workpiece decreases. Conversely, if the abrasive grain size is too small, it is prone to agglomeration, increasing surface scratches. For different types of polishing slurries, silicon oxide slurries can achieve a smaller surface roughness but generally have a slower removal rate; while alumina slurries have a faster removal rate, the large abrasive consumption, limited by the mechanical properties of the abrasive itself, has become a bottleneck for improving efficiency; diamond slurries, although having sufficient hardness, also introduce abrasive grain adhesion problems and are difficult to overcome in causing surface scratches on wafers.

[0004] Therefore, there is a need to provide an improved technical solution to address the shortcomings of existing polishing slurries, in order to ensure the polishing effect of wafers and the quality of polished products. Summary of the Invention

[0005] In view of the defects and deficiencies in the existing wafer polishing technology described above, the purpose of this application is to provide a wafer abrasive, a polishing slurry, a preparation method thereof, and an application thereof, by modifying the abrasive and preparing a polishing slurry containing the modified abrasive to solve the above-mentioned problems in the prior art.

[0006] In a first aspect, this application provides a wafer abrasive having a core-shell structure, the core-shell structure comprising at least a core layer and an outer shell layer covering the surface of the core layer, wherein...

[0007] The core layer is made of silicon carbide micro powder;

[0008] The outer shell is made of hyperbranched polycarbosilane with hydrophilic groups.

[0009] Secondly, this application provides a method for preparing a wafer abrasive, comprising the following steps:

[0010] Silicon carbide micro powder is provided;

[0011] Silicon carbide micro powder was impregnated in dihalosilane, and intermediate A1 with polydimethylsilane coated on the surface of silicon carbide micro powder was obtained by polymer impregnation pyrolysis method.

[0012] Intermediate A1 undergoes a rearrangement reaction under high temperature conditions to obtain intermediate A2, which is coated with polycarbosilane on the surface of silicon carbide micropowder.

[0013] Heating intermediate A2 and reacting it with hydrogen halide under the action of a catalyst yields intermediate A3, which is coated with halogenated polycarbosilane on the surface of silicon carbide micropowder.

[0014] When intermediate A3 is heated in an alkaline environment, the halopolycarbosilane in its outer shell layer hydrolyzes into hydroxypolycarbosilane, resulting in a silicon carbide core-shell abrasive B1 coated with hydroxypolycarbosilane.

[0015] Thirdly, this application provides a polishing liquid, wherein the polishing liquid has the following component proportions by weight:

[0016] 1 to 60 parts of the wafer abrasive as described in any of the above technical solutions;

[0017] Surfactant, 0.01~5 parts;

[0018] Dispersant, 1-30 parts;

[0019] Chelating agent, 0.01~5 parts;

[0020] pH adjuster, 0.1~30 parts;

[0021] Deionized water, 50-97 parts.

[0022] Fourthly, this application provides a method for preparing a polishing slurry, comprising the following steps:

[0023] Add a surfactant to deionized water and stir to form a homogeneous solution;

[0024] Under stirring conditions, wafer abrasive is added to the homogeneous solution, and stirring is continued until the surfactant and wafer abrasive are in full contact.

[0025] Under stirring conditions, continue adding the dispersant and continue stirring to form a stable dispersion solution;

[0026] A chelating agent was added to the stable dispersion system solution, and the mixture was stirred to obtain a solution without a boundary layer.

[0027] A pH adjuster is added to the solution without a boundary layer to adjust the pH to an alkaline range of 7-14, thus obtaining a polishing solution.

[0028] Fifthly, this application also provides the application of the wafer abrasive or polishing slurry described in the above technical solutions in sapphire processing.

[0029] Compared with the prior art, the technical solution provided in this application has the following beneficial effects:

[0030] In this application's technical solution, the abrasive is organically modified to create a core-shell structure. The polycarbosilane outer shell with hydrophilic groups effectively enhances abrasive adhesion and removal capabilities, while the high-strength silicon carbide micropowder core maintains the polishing removal amount. During use, the polishing slurry, operating in a high-pH environment, generates a strong chemical reaction, enabling the self-reactivation of the hyperbranched modified chains in the abrasive and resulting in cyclical chemical removal capabilities. This effectively eliminates scratches on the wafer surface. The wafer abrasive and polishing slurry provided in this application are also used for precisely controlling the surface roughness of products, improving abrasive removal efficiency, and significantly reducing abrasive consumption and production costs. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the wafer abrasive provided in Embodiment 1 of this application;

[0032] Figure 2 This is a flowchart of the wafer abrasive preparation method provided in Embodiment 1 of this application;

[0033] Figure 3 This is a flowchart of the polishing slurry preparation method provided in Example 2 of this application;

[0034] Figure 4 Infrared detection spectrum of wafer abrasive B1 provided in Embodiment 1 of this application;

[0035] Figure 5 Infrared detection spectrum of wafer abrasive B3 provided in Embodiment 1 of this application.

[0036] Explanation of reference numerals in the attached figures:

[0037] 100, Kernel layer; 200, Middle layer; 300, Outer layer. Detailed Implementation

[0038] Sapphire substrates are widely used in the semiconductor industry due to their high flatness and intact crystal structure. Sapphire has a Mohs hardness of 9, making sapphire wafers highly sensitive to the hardness of the polishing slurry during polishing. Existing polishing slurries are classified into several categories based on their main components, including diamond polishing slurries, silicon oxide polishing slurries, cerium oxide polishing slurries, aluminum oxide polishing slurries, and silicon carbide polishing slurries. Different types and proportions of polishing slurries are selected for substrates of different materials and with varying polishing quality requirements.

[0039] When using silicon oxide polishing slurry, a smaller surface roughness can be obtained, but the removal rate is generally slow. Although aluminum oxide polishing slurry has a faster removal rate, the huge abrasive consumption has become a bottleneck for improving efficiency due to the limitations of the mechanical properties of the abrasive itself. Although diamond polishing slurry has high hardness, it also brings the problem of abrasive adhesion and it is difficult to overcome the surface scratches on the wafer. Silicon carbide has a Mohs hardness of up to 9.2 or even 9.5, and the polishing slurry prepared with it will also cause surface scratches.

[0040] To address the above deficiencies, this application provides a wafer abrasive having a core-shell structure, wherein the core-shell structure includes at least a core layer and an outer shell layer covering the surface of the core layer, wherein...

[0041] The core layer is made of silicon carbide micro powder;

[0042] The outer shell is made of hyperbranched polycarbosilane with hydrophilic groups.

[0043] By adopting the above technical solution, the abrasive is organically modified and designed with a core-shell structure. The polycarbosilane outer shell with hydrophilic groups effectively improves the abrasive adhesion and removal capabilities, while the high-strength silicon carbide micropowder core layer maintains the polishing removal amount. During use, the polishing slurry, in conjunction with a high-pH environment, generates a strong chemical reaction, enabling the self-reactivation of the hyperbranched modified chains in the abrasive and resulting in cyclical chemical removal capabilities. This effectively eliminates scratches on the wafer surface. The wafer abrasive and polishing slurry provided in this application can also be used to precisely control the surface roughness of products, improve abrasive removal efficiency, and significantly reduce abrasive consumption and production costs.

[0044] In some embodiments, the hydrophilic group is a hydroxyl or carboxyl group. The hydroxyl or carboxyl groups of the hyperbranched polymer branches can rapidly capture the hydrogen bond structure of hydrated alumina during chemical mechanical removal, allowing the polishing particles to detach from the wafer surface via the abrasive, thus improving removal efficiency.

[0045] In some embodiments, the average particle size D50 of the silicon carbide micropowder is 0.5-2.5 μm;

[0046] The Mohs hardness of the silicon carbide micro powder is 9.2~9.5.

[0047] In some embodiments, an intermediate layer is further provided between the core layer and the outer shell layer. This intermediate layer is a cross-linked structural layer formed by silicon carbide and partially thermally decomposed polycarbosilane. This cross-linked structural layer enables the polymer outer shell layer to form better adhesion with the inorganic material core layer, making the core-shell structure more stable. The hyperbranched polymer of the outer shell layer can be regenerated and recycled during the polishing process, reducing abrasive wear.

[0048] This application also provides a method for preparing a wafer abrasive, comprising the following steps:

[0049] Silicon carbide micro powder is provided;

[0050] Silicon carbide micro powder was impregnated in dihalosilane, and intermediate A1 with polydimethylsilane coated on the surface of silicon carbide micro powder was obtained by polymer impregnation pyrolysis method.

[0051] Intermediate A1 undergoes a rearrangement reaction under high temperature conditions to obtain intermediate A2, which is coated with polycarbosilane on the surface of silicon carbide micropowder.

[0052] Heating intermediate A2 causes it to undergo a substitution reaction with hydrogen halide under the action of a catalyst, yielding intermediate A3 with halogenated polycarbosilane coated on the surface of silicon carbide micropowder.

[0053] When intermediate A3 is heated in an alkaline environment, the halopolycarbosilane in its outer shell layer hydrolyzes into hydroxypolycarbosilane, resulting in a silicon carbide core-shell abrasive B1 coated with hydroxypolycarbosilane.

[0054] By employing the above technical solution, using dihalosilane as raw material, intermediate A1 with a polydimethylsilane shell layer is initially formed on the surface of silicon carbide micropowder through impregnation and pyrolysis. Then, through high-temperature rearrangement, the polydimethylsilane shell layer is transformed into a polycarbosilane shell layer, yielding intermediate A2. Next, the polycarbosilane shell layer undergoes a substitution reaction with hydrogen halide to transform into a halopolycarbosilane shell layer, yielding intermediate A3. Finally, intermediate A3 undergoes a hydrolysis reaction, where the halogens in the polymer branches are replaced by hydroxyl groups, yielding a hydroxyl polycarbosilane shell layer. This structure, where the silicon carbide core layer is coated with this hydroxyl polycarbosilane shell layer, can serve as a wafer abrasive, namely wafer abrasive B1, participating in the preparation of polishing slurries and the polishing process.

[0055] In some embodiments, after obtaining a silicon carbide core-shell structured wafer abrasive B1 coated with hydroxyl polycarbosilane, the wafer abrasive B1 is heated to cause it to decompose, resulting in a wafer abrasive B2 with a hydroxyl radical core-shell structure. The outer shell hydroxyl groups of the wafer abrasive B1 are further thermally decomposed and ceramicized, transforming the hydroxyl groups into free ends with stronger adhesion, making them easier to bond with hydrogen bonds.

[0056] In some embodiments, during the pyrolysis of wafer abrasive B1, hydroxyl polycarbosilane near the core layer of silicon carbide microparticles simultaneously generates silicon carbide, resulting in a cross-linked structural layer formed by silicon carbide and partially pyrolyzed polycarbosilane. While the outermost layer of the wafer abrasive B1 captures polishing products, it also enhances the bonding force between the innermost layer of the outer shell and the silicon carbide microparticles, making the structure of wafer abrasive B1 more stable and improving removal effect and efficiency.

[0057] In some embodiments, after obtaining a core-shell structured wafer abrasive B1 with hydroxyl polycarbosilane coating on silicon carbide, wafer abrasive B1 is oxidized under chromium trioxide and acetic acid conditions to obtain a core-shell structured wafer abrasive B3 with carboxyl polycarbosilane coating on silicon carbide. The hydroxyl groups in the outer shell layer of wafer abrasive B1 are further oxidized to carboxyl groups, enhancing the bonding force between the outer shell polymer and hydrogen bonds, and improving the abrasive's trapping ability and removal capacity.

[0058] In some embodiments, the wafer abrasive B3 is heated to cause it to decompose, and the carboxyl polycarbosilane near the core layer of silicon carbide microparticles is converted into silicon carbide, resulting in a cross-linked structural layer formed by silicon carbide and partially thermally decomposed polycarbosilane. The outermost layer of the wafer abrasive B3 outer shell has high trapping capacity, while simultaneously enhancing the bonding force between the innermost layer and the silicon carbide microparticles, making the structure of the wafer abrasive B3 more stable and improving its removal effect and efficiency.

[0059] This application also provides a polishing liquid, wherein the polishing liquid has the following component proportions by weight:

[0060] 1 to 60 parts of the wafer abrasive as described in any of the above technical solutions;

[0061] Surfactant, 0.01~5 parts;

[0062] Dispersant, 1-30 parts;

[0063] Chelating agent, 0.01~5 parts;

[0064] pH adjuster, 0.1~30 parts;

[0065] Deionized water, 50-97 parts.

[0066] By adopting the above technical solution, configuring a polishing slurry with high adhesion and spreading ability, and controlling the type and amount of each additive, the surface roughness of the processed sapphire wafer can reach 0.1nm~0.6nm, and the removal efficiency can be improved by 2%~30%. The unit removal consumption of abrasive is also effectively reduced, thereby reducing the material cost in the polishing process.

[0067] In some embodiments, the surfactant is a water-soluble reagent with a sulfonic acid group, including one or more of sodium dodecylbenzenesulfonate, sodium polyoxyethylene sulfate, or polyoxyethylene sulfonate. Surfactants with sulfonic acid groups can modify the surface of the polymer shell layer of the wafer abrasive, thereby adjusting the polishing efficiency of the polishing slurry. They also facilitate the removal of materials such as byproducts from the polishing process, preventing residual substances on the surface after polishing from affecting the consistency of wafer performance, and can also prevent the agglomeration of micronized powder particles.

[0068] In some embodiments, the dispersant comprises a hyperbranched hydrophilic polymer. As an example, the hyperbranched hydrophilic polymer may be comb-shaped PAA-PEO (comb-shaped polyacrylic acid-polyethylene oxide).

[0069] In some embodiments, the dispersant further includes one or more of sodium nitrate, sodium oxalate, sodium hexametaphosphate, sodium pyrophosphate, or sodium tripolyphosphate. The addition of the dispersant can interact with the surface of the wafer abrasive shell layer, altering the surface properties of the shell layer polymer and contributing to the stability of the abrasive surface zeta potential.

[0070] In some embodiments, the chelating agent is a polyol and / or a polycarboxylic acid; the chelating agent includes one or more of ethylenediaminetetraacetic acid, sodium tartrate, or sorbitol. The chelating agent can form stable complexes with metal ions, increasing the amount removed during polishing and providing a buffer for the polishing slurry, thus making the dispersion system more stable.

[0071] In some embodiments, the pH range of the polishing slurry is 7-14. Further, the pH range of the polishing slurry is 13.0-13.5. Adjusting the polishing slurry system to an alkaline or even strongly alkaline environment is beneficial for the self-resurrection of the outer shell layer, allowing the wafer abrasive to be recycled and used efficiently.

[0072] In some embodiments, the pH adjuster includes one or more of potassium hydroxide, ammonia, potassium / sodium carbonate, potassium / sodium bicarbonate, sodium / potassium hexametaphosphate, sodium laurate, and sodium oxalate. Water-soluble alkaline reagents such as strong-base-weak-acid salts are selected to precisely adjust the pH of the polishing solution system.

[0073] This application also provides a method for preparing a polishing slurry, comprising the following steps:

[0074] Add a surfactant to deionized water and stir to form a homogeneous solution;

[0075] Under stirring conditions, wafer abrasive is added to the homogeneous solution, and stirring is continued until the surfactant and wafer abrasive are in full contact.

[0076] Under stirring conditions, continue adding the dispersant and continue stirring to form a stable dispersion solution;

[0077] A chelating agent was added to the stable dispersion system solution, and the mixture was stirred to obtain a solution without a boundary layer.

[0078] A pH adjuster is added to the solution without a boundary layer to adjust the pH to an alkaline range of 7-14, thus obtaining a polishing solution.

[0079] By adopting the above technical solution, a polishing slurry with a stable system, good uniformity, and suitable wafer abrasive concentration is formed, so as to achieve the best combination of mechanical and chemical action and improve the abrasive removal rate.

[0080] This application also provides an application of the wafer abrasive or polishing slurry described in the above-mentioned technical solutions in sapphire processing. During the polishing process of sapphire wafers, due to the self-healing and recyclable characteristics of the wafer abrasive provided in this application, the actual wear rate of the wafer abrasive is 0.5%-5%, significantly reducing the wafer wear rate. The wafer abrasive provided in this application demonstrates excellent performance in this field.

[0081] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.

[0082] The main raw materials used in the embodiments of this application are as follows:

[0083] (1) Silicon carbide micro powder: Henan Kangtai Micro Powder Co., Ltd., GC 6000# for abrasives (GC content 99.0%~99.9%, oxide content <0.1%, carbide content <0.5%, nitride content <0.1%, boride content <0.1%, metal impurity content <0.2%).

[0084] (2) Dihalosilanes: Shanghai Zhixin Chemical Co., Ltd., purity >95%;

[0085] (3) Comb-shaped PAA-PEO: Nanjing Xiaoke Nanoceramics Technology Development Co., Ltd., number average molecular weight 8000-8500;

[0086] Other raw materials used in the embodiments, unless otherwise specified, are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0087] Example 1:

[0088] See Figures 1-2 This embodiment provides a wafer abrasive and a method for preparing the wafer abrasive. The preparation process of the wafer abrasive is as follows:

[0089] S100: Provides silicon carbide micro powder as the core layer 100 material for wafer abrasives;

[0090] S200: Using dihalosilane as the outer shell layer 300 material for wafer abrasive, silicon carbide micro powder is impregnated in dihalosilane, and a polymer impregnation pyrolysis method is adopted to initially form an intermediate A1 with a polydimethylsilane outer shell layer 300 on the surface of silicon carbide micro powder through impregnation pyrolysis.

[0091] S300: Intermediate A1 undergoes a rearrangement reaction under high temperature conditions, converting polydimethylsilane into polycarbosilane, to obtain intermediate A2 with polycarbosilane coated on the surface of silicon carbide micro powder.

[0092] S400: Heating intermediate A2, the outer shell layer 300 of intermediate A2, polycarbosilane, undergoes a substitution reaction with hydrogen halide under the action of a catalyst, and polycarbosilane is converted into halopolycarbosilane, resulting in intermediate A3 with halopolycarbosilane coated on the surface of silicon carbide micro powder.

[0093] S500: When intermediate A3 is heated in an alkaline environment, it undergoes a hydrolysis reaction, and the halogen of the halopolysilane in its outer shell 300 is replaced by hydroxyl groups to generate hydroxyl polysilane, thus obtaining a silicon carbide core-shell abrasive B1 with hydroxyl polysilane coating.

[0094] The structure of the silicon carbide core layer 100 coated with the hydroxyl polycarbosilane outer shell layer 300 can serve as a wafer abrasive, namely wafer abrasive B1, and participate in the preparation of polishing slurry and polishing process to achieve good polishing effect. The silicon carbide micropowder, as the high-strength and wear-resistant core layer 100, ensures effective friction when the wafer abrasive B1 contacts the wafer surface. Simultaneously, the polymer outer shell layer 300, coated with silicon carbide micropowder, has hyperbranched molecular chains. Under the pressure and dragging action of the polishing pad and the wafer during the friction process, the branches of the hyperbranched outer shell layer 300 develop a certain orientation, forming a fibrous, densely packed structure. This achieves the microstructure of a sheet-like wafer abrasive, which provides a certain degree of protection to the wafer surface, preventing surface scratches. Furthermore, the surface roughness of the wafer polishing can be precisely controlled by adjusting the particle size of the silicon carbide micropowder and the branching degree of the outer shell layer 300. The surface roughness of products processed with polishing slurry prepared using the wafer abrasive provided in this application can reach 0.1 nm to 0.6 nm.

[0095] The following details the fabrication process of this wafer abrasive:

[0096] S100: Provides silicon carbide micro powder as the core layer 100 material for wafer abrasives;

[0097] Specifically, silicon carbide micropowder with an average particle size of D50 of 0.5 μm to 2.5 μm and a Mohs hardness of 9.2 to 9.5 is selected. It is understandable that as the abrasive particle size in the polishing slurry increases, the surface removal rate of the sapphire wafer increases, but at the same time, scratches increase, and the surface quality of the wafer decreases. However, if the abrasive particle size is too small, it is prone to agglomeration during polishing, affecting the utilization rate of the polishing slurry. To further improve the dispersion of abrasive particles in the polishing slurry and enhance the polishing effect, as well as increase the lubrication performance of the polishing slurry, the silicon carbide micropowder used in this embodiment is selected in the range of 1000 nm to 5000 nm. The uniform particle size of the silicon carbide micropowder results in more uniform friction with the polished surface, thereby reducing the surface roughness of the wafer and achieving superior polishing quality.

[0098] S200: Using dihalosilane as the outer shell layer 300 material for wafer abrasive, silicon carbide micro powder is impregnated in dihalosilane, and a polymer impregnation pyrolysis method is adopted to initially form an intermediate A1 with a polydimethylsilane outer shell layer 300 on the surface of silicon carbide micro powder through impregnation pyrolysis.

[0099] Specifically, the synthesis route for coating a polydimethylsilane outer shell layer 300 onto the surface of silicon carbide micropowder is as follows: Silicon carbide micropowder impregnated with dihalosilane is refluxed for 20 hours in a solvent of hexane and tetrahydrofuran with sodium metal as a catalyst. The silicon carbide core layer 100 does not participate in the reaction, and the dihalosilane is used to synthesize the polydimethylsilane outer shell layer 300. The dihalosilane can be dichlorosilane, chloromethyltrichlorosilane, chloromethyltrichlorosilane, chloromethyltrichlorosilane propane, etc.; and raw materials such as 1,1,3,3-tetrachloro-1,3-disilpropane, 1,1,3,3-tetrachloro-1,3-disilbutane, and 1,1,3,3-tetrachloro-1,3-disilpentane.

[0100] The reaction equation is as follows:

[0101]

[0102] Where X is a halogen, such as chlorine, bromine or iodine.

[0103] Alternatively, the synthesis route for coating the surface of silicon carbide micropowder with a polydimethylsilane outer shell layer 300 can also be:

[0104]

[0105] Alternatively, the synthesis route for coating the surface of silicon carbide micropowder with a polydimethylsilane outer shell layer 300 can also be:

[0106] S300: Intermediate A1 undergoes a rearrangement reaction under high temperature conditions, converting polydimethylsilane into polycarbosilane, to obtain intermediate A2 with polycarbosilane coated on the surface of silicon carbide micro powder.

[0107] Specifically, polydimethylsilane is heated to 400°C, and the polydimethylsilane undergoes a rearrangement reaction under high-temperature conditions to synthesize polycarbosilane. The silicon carbide micropowder core layer 100 does not participate in the reaction, yielding intermediate A2 with polycarbosilane coating on its surface. The synthetic route is as follows:

[0108]

[0109] S400: Heating intermediate A2, the polycarbosilane shell layer 300 of intermediate A2 undergoes a substitution reaction with hydrogen halide under the action of a catalyst, and the polycarbosilane is converted into halopolycarbosilane, resulting in intermediate A3 with halopolycarbosilane coated on the surface of silicon carbide micro powder.

[0110] Specifically, sodium iodide is used as a catalyst. Polycarbosilane and hydrogen halide undergo a substitution reaction between 50℃ and 200℃. The hydrogen atom in the methyl group attached to silicon is replaced by the halogen, yielding a halopolycarbosilane. The core layer 100 of the silicon carbide micropowder does not participate in the reaction, thus obtaining intermediate A3, which is coated with halopolycarbosilane on the surface of silicon carbide micropowder. The synthetic route is as follows:

[0111]

[0112] S500: Intermediate A3 undergoes hydrolysis upon heating in an alkaline environment. The halogens in the halopolysilane of its outer shell layer 300 are replaced by hydroxyl groups, further hydroxylating to generate hydroxyl polysilane. The silicon carbide micropowder core layer 100 does not participate in the reaction, resulting in a core-shell structured wafer abrasive B1 coated with hydroxyl polysilane. The synthesis route is as follows:

[0113]

[0114] After the above series of reactions, the structure of the silicon carbide core layer 100 covered by the hydroxyl polycarbosilane outer shell layer 300 can be used as a wafer abrasive, namely wafer abrasive B1, and participate in the preparation of polishing slurry and polishing process.

[0115] Appendix Figure 4 The infrared spectrum of the surface coating material of wafer abrasive B1 is shown. The peak of OH stretching vibration is at 3333 cm-1 and the peak of CO stretching vibration is at 1052 cm-1. The detection results confirm that the outer shell layer 300 of wafer abrasive B1 is a polymer material with -CH2OH.

[0116] During wafer polishing, the silicon carbide micropowder in the core layer 100 provides sufficient hardness for polishing, ensuring effective friction between the wafer abrasive and the wafer. Especially for sapphire wafers whose main component is alumina, during the wetting process of the polishing slurry and the high-speed friction with the wafer abrasive, the Al2O3 on the surface of the sapphire wafer combines with water molecules H2O to form a thin layer of hydrated alumina AlO(OH)·nH2O. Meanwhile, the hydroxyl-OH groups in the hydroxyl polycarbosilane in the outer shell layer 300 can quickly capture the hydrogen bonds in the hydrated alumina, causing the surface waste material generated during polishing (polishing products, the same below) to be adsorbed by the wafer abrasive. As the polishing slurry is discharged, the polishing products are carried away from the wafer surface, preventing material agglomeration or residue on the wafer surface, which would affect the further contact and friction effect between the abrasive and the sapphire wafer, and also improving the polishing efficiency.

[0117] S600: After obtaining the core-shell structured wafer abrasive B1 with hydroxyl polycarbosilane coating on silicon carbide, the outer shell layer 300 of the wafer abrasive B1 can be further modified to obtain an outer shell layer 300 with higher removal efficiency and / or a core-shell structured abrasive with stronger structural stability. This step specifically includes two modification methods, S600a and S600b. S600a involves high-temperature pyrolysis of the outer shell layer 300 to enhance the hydroxyl group capture ability, while generating a self-healing and recyclable wafer abrasive B2. S600b involves oxidizing the outer shell layer 300 to oxidize the terminal hydroxyl groups to carboxyl groups, obtaining wafer abrasive B3. By changing the chemical properties of the groups, its ability to capture hydrogen bonds in hydrated alumina is improved, thereby enhancing the abrasive removal effect.

[0118] Depending on the type of polishing product and its surface properties, different methods can be used to obtain modified wafer abrasive B2 or wafer abrasive B3 to meet actual application requirements. The two modification methods and their principles are detailed below:

[0119] S600a: A wafer abrasive B1 is heated to induce a pyrolysis reaction at a temperature of 410℃~900℃ for 1h~5h. This further thermally decomposes and ceramicizes the hydroxyl groups in the outer shell layer 300 of wafer abrasive B1, yielding wafer abrasive B2 with a hydroxyl radical core-shell structure. During the thermal pyrolysis process, the hydroxyl groups are converted into the more adhesive free-terminal -COH-. Therefore, wafer abrasive B2 binds more easily to hydrogen bonds in hydrated alumina than wafer abrasive B1, exhibiting stronger bonding and higher removal efficiency for polished products. The modification pathway is as follows:

[0120]

[0121] Simultaneously, during the pyrolysis of the outer shell layer 300 of the wafer abrasive B1, the hydroxyl polycarbosilane near the silicon carbide micropowder core layer 100 partially participates in the reaction at high temperature, generating a silicon carbide polymer. This results in a cross-linked structural layer formed by silicon carbide and partially thermally decomposed polycarbosilane, namely the intermediate layer 200. It can be understood that the intermediate layer 200 is not a sandwich structure with fixed boundaries, but rather a doped structural layer located between the core layer 100 and the outer shell layer 300. This doped structural layer further enhances the structural stability of the wafer abrasive, greatly improving its service life and saving abrasive consumable costs. The reaction principle is as follows:

[0122]

[0123]

[0124] As can be seen from the above reaction process, as polycarbosilane is continuously synthesized into silicon carbide, the polymer branches of the outer shell layer 300 are also gradually growing. Within a wide reaction temperature range of 410℃ to 900℃ and a wide reaction time range of 1h to 5h, only a portion of the polycarbosilane in the outer shell layer 300 will decompose to form the final product hyperbranched silicon carbide. Since the hyperbranched silicon carbide and the silicon carbide micropowder in the core layer 100 have more similar chemical properties to a certain extent, their bonding strength is also greater than that of polycarbosilane and silicon carbide micropowder in the wafer abrasive B1. Therefore, by forming an intermediate layer 200 that crosslinks hyperbranched silicon carbide and hyperbranched polycarbosilane, the polymer outer shell layer 300 and the inorganic material core layer 100 form a better adhesion, the shell-core structure is more stable, the wafer abrasive B2 can be recycled multiple times to reduce abrasive wear and save on the consumable cost of polishing fluid. Furthermore, when the polishing slurry is alkaline, during the process of the hydrated alumina thin layer being captured and detached from the wafer by the abrasive, alumina Al2O3 reacts with hydroxide ions (OH-). - The resulting flocculent aluminum hydroxide (Al(OH)3) precipitate becomes entangled on the hyperbranched outer shell layer 300 and is then pulled away from the wafer surface. This portion of the flocculent Al(OH)3 precipitate continues to react in an alkaline environment, gradually transforming into soluble aluminate (AlO2). - The ionic solution detaches from the surface of the wafer abrasive B2 and re-dissolves in the polishing slurry. Therefore, the wafer abrasive B2 that participated in the polishing process achieves self-resurrection as the polishing slurry is discharged. The self-resurrected wafer abrasive B2 can be reused in the polishing slurry process while maintaining the initial high adsorption level and good polishing ability.

[0125] Understandably, thermal decomposition will also produce hyperbranched polycarbosilanes with highly active hydroxyl groups, as well as intermediate polymer products in each of the above reaction steps, which will not be elaborated here.

[0126] In summary, hyperbranched hydroxyl polycarbosilane and hyperbranched silicon carbide enhance the ability to trap polishing products and strengthen the abrasive structure, respectively, resulting in a significant improvement in the performance of wafer abrasives. Specifically, while the outermost layer of the outer shell 300 of wafer abrasive B1 traps polishing products, the bonding force between the innermost layer of the outer shell 300 and the silicon carbide micropowder is also enhanced, making the structure of wafer abrasive B2 more stable, with higher removal effect and efficiency. At the same time, the outer shell 300 also has a self-recovery capability, greatly saving the amount of abrasive used.

[0127] S600b: After obtaining a core-shell structured wafer abrasive B1 with hydroxyl polycarbosilane coating on silicon carbide, wafer abrasive B1 is oxidized under the conditions of chromium trioxide and acetic acid (glacial acetic acid) to obtain a core-shell structured wafer abrasive B3 with carboxyl polycarbosilane coating on silicon carbide. The hydroxyl groups in the outer shell layer of wafer abrasive B1 are further oxidized to carboxyl groups, enhancing the binding force between the outer shell polymer and hydrogen bonds, thereby improving the abrasive's trapping ability and removal capacity. The modification route is as follows:

[0128]

[0129] Appendix Figure 5 The infrared spectrum of the surface coating material of wafer abrasive B3 is shown. The peak at 1700~1800cm-1 is the CO stretching vibration peak, and the peak at 2800~3400cm-1 is the OH association peak. Based on the detection results, it can be confirmed that the outer shell layer 300 of wafer abrasive B3 is a polymer material with -COOH.

[0130] In some embodiments, the wafer abrasive B3 can be further heated to cause it to decompose. The reaction temperature is 410℃~900℃, and the reaction time is 1h~5h. The hydrocarbon groups of the carboxylated polycarbosilane continue to decompose to generate silicon carbide polymer, resulting in a cross-linked structural layer formed by silicon carbide and partially decomposed polycarbosilane, i.e., the intermediate layer 200. The outermost layer of the wafer abrasive B3 outer shell layer 300 has high capture capacity, while enhancing the bonding force between the innermost layer of the outer shell layer 300 and the silicon carbide micropowder, making the wafer abrasive B3 structure more stable and improving the removal effect and efficiency. It is understood that the intermediate layer 200 obtained by the partial thermal decomposition reaction in the modification method provided by S600b has the same excellent bonding performance as the intermediate layer in S600a, which greatly improves the stability and structural strength of the abrasive itself, and will not be elaborated here.

[0131] The wafer abrasives B1, B2, and B3 provided in Example 1 are all core-shell modified abrasives with a hydrophilic hyperbranched polycarbosilane outer shell layer 300 covering a silicon carbide micropowder core layer 100. The removal rate of the modified wafer abrasives can be increased by 2% to 30%, and the unit removal consumption of the wafer abrasives can be reduced by 5% to 5000% compared with traditional alumina abrasives.

[0132] In addition, the polishing pads used in the CMP process are usually made of polyurethane (PU). The N and O elements in the urethane structure and amide structure of the polyurethane polishing pad have lone pairs of electrons. These lone pairs of electrons can form hydrogen bonds with the hydroxyl and carboxyl groups in the wafer abrasive, which enhances the adhesion and adsorption between them, thereby further releasing the mechanical processing capability of the wafer abrasive.

[0133] Example 2:

[0134] See Figure 3 This embodiment provides a polishing slurry and a method for preparing the polishing slurry. The polishing slurry has the following component proportions by weight:

[0135] 1 to 60 parts of wafer abrasive B1, wafer abrasive B2 or wafer abrasive B3 provided in Example 1;

[0136] Surfactant, 0.01~5 parts;

[0137] Dispersant, 1-30 parts;

[0138] Chelating agent, 0.01~5 parts;

[0139] pH adjuster, 0.1~30 parts;

[0140] Deionized water, 50-97 parts.

[0141] Understandably, as the concentration of abrasive particles in the polishing slurry increases, the wafer removal rate also increases. However, when the concentration of abrasive particles reaches a certain value, the removal rate will stop increasing and remain at a constant, reaching the material removal saturation line. Simultaneously, due to the increased concentration of the polishing slurry and the intensified friction between the abrasive particles and the wafer surface, surface scratches actually increase, leading to a decrease in surface quality. The above-mentioned polishing slurry ratio represents a reasonable range that achieves good polishing results from the abrasive particles, balancing wafer surface removal rate, flatness, polishing efficiency, and consumable costs, achieving the optimal combination of mechanical and chemical action.

[0142] The polishing slurry prepared using the above technical solution has a high-efficiency adhesion and spreading ability. By adjusting the type and amount of each additive, the surface roughness of the processed sapphire wafer can reach 0.1nm~0.6nm, and the removal efficiency can be improved by 2%~30%. The unit removal consumption of abrasive is also effectively reduced by 5%~5000%, and the consumable cost in the polishing process is greatly reduced.

[0143] The preparation process of this polishing slurry will be described in detail below:

[0144] Unless otherwise specified, all reagent quantities used in the following preparation processes are by weight.

[0145] S10: First, add the surfactant to the deionized water and stir to form a homogeneous solution;

[0146] Specifically, the surfactant is a water-soluble reagent with sulfonic acid groups. Surfactants with sulfonic acid groups can modify the surface of the polymer shell layer 300 of the wafer abrasive, reducing the surface tension of the polishing slurry and thus adjusting the polishing efficiency. Simultaneously, they facilitate the removal of materials such as byproducts from the polishing process, preventing residual substances from affecting the uniformity of wafer performance and inhibiting the agglomeration of wafer abrasive particles. As an example, the surfactant can be one or more of sodium dodecylbenzenesulfonate, sodium polyoxyethylene sulfate, or polyoxyethylene sulfonate.

[0147] S20: Under stirring conditions, add wafer abrasive to the above homogeneous solution and continue stirring until the surfactant and wafer abrasive are in full contact.

[0148] Specifically, the addition rate of the wafer abrasive is based on the principle of not producing large particle agglomerates. The wafer abrasive can be any one or more of the wafer abrasive B1, wafer abrasive B2 or wafer abrasive B3 provided in Example 1. The stirring time ranges from 1 min to 30 min. To ensure that the surfactant and the wafer abrasive are in full contact, this step can be set to stirring for 30 min.

[0149] S30: Under stirring conditions, continue to add dispersant and continue stirring to form a stable dispersion system solution;

[0150] Specifically, the dispersant comprises at least a hyperbranched hydrophilic polymer and an inorganic dispersant. As an example, the hyperbranched hydrophilic polymer can be comb-shaped PAA-PEO (comb-shaped polyacrylic acid-polyethylene oxide). The unique comb-like structure of comb-shaped PAA-PEO allows the PAA-PEO copolymer to anchor at multiple points on the particle surface, forming a sufficiently thick adsorption layer and a sufficient number of adsorption sites, thus exhibiting superior dispersion performance. Furthermore, in the molecular structure of the PAA-PEO copolymer, the lengths of PAA and PEO (the number of PAA segments m and the number of PEO segments n) can be adjusted by the raw material addition ratio. By adjusting the amount of other additives in the polishing solution, different types of comb-shaped PAA-PEO can be selected to obtain a polishing solution with better dispersion. The chemical structural formula of comb-shaped PAA-PEO is as follows:

[0151]

[0152] As an example, inorganic dispersants include one or more of sodium nitrate, sodium oxalate, sodium hexametaphosphate, sodium pyrophosphate, or sodium tripolyphosphate. Both organic and inorganic dispersants can interact with the surface of the wafer abrasive shell layer 300, altering the surface properties of the shell layer 300 polymer and contributing to the stability of the zeta potential on the wafer abrasive surface. The stirring time for the dispersant ranges from 1 min to 30 min; to ensure a stable polishing slurry system, this step can be set to stirring for 30 min.

[0153] S40: Add a chelating agent to the above stable dispersion system solution and stir to obtain a solution without a boundary layer;

[0154] Specifically, the chelating agent is a polyol and / or a polycarboxylic acid. As an example, the chelating agent can be one or more of EDTA (ethylenediaminetetraacetic acid), sodium tartrate, or sorbitol. The chelating agent can form a stable complex with metal ions, increasing the polishing removal amount and rate, and providing a buffer for the polishing slurry, making the dispersion system more stable. The stirring time for the chelating agent ranges from 1 min to 30 min; to ensure the formation of a stable complex system in the polishing slurry, this step can be set to stirring for 30 min.

[0155] S50: Add a pH adjuster to the above solution without a boundary layer to adjust the pH to an alkaline range of 7-14 to obtain a polishing solution.

[0156] Specifically, the final polishing solution has a pH range of 7–14. Further, the pH range of the polishing solution is 13.0–13.5. When the polishing solution system is in an alkaline environment, there are a large number of free hydroxide ions (OH-) in the solution. - During the high-speed friction of the alumina on the surface of a sapphire wafer with water molecules, the AlO(OH)·nH2O thin layer formed is carried away from the wafer surface by the abrasive and continues to react with hydroxide ions to transform into soluble aluminate ions (AlO2). - The ionic solution detaches from the surface of the wafer abrasive and redissolves in the polishing solution. Therefore, the alkaline environment allows the wafer abrasive involved in polishing to self-reactivate as the polishing solution is discharged. Within a certain range, the stronger the alkalinity, the stronger the activation ability. The self-activated wafer abrasive can be reused in the polishing solution process while maintaining its initial high adsorption level and good polishing ability. As an example, the pH adjuster mentioned above includes one or more of potassium hydroxide, ammonia, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, sodium hexametaphosphate, potassium hexametaphosphate, sodium laurate, and sodium oxalate. Using water-soluble strong base-weak acid salts and other alkaline reagents to adjust the pH of the polishing solution system is faster and more accurate.

[0157] By adding the above-mentioned additives and adjusting the additive ratio, a polishing slurry with a stable system, good uniformity, and suitable wafer abrasive concentration is formed, so as to achieve the best combination of mechanical and chemical action, and improve the abrasive removal rate and polishing quality.

[0158] Example 3:

[0159] This embodiment provides a method for preparing a polishing slurry: First, weigh 97 parts of deionized water, add 0.01 parts of sodium dodecylbenzenesulfonate (a surfactant) to the deionized water, and stir to form a homogeneous solution; then, under continuous stirring, add 1 part of wafer abrasive B1 to the homogeneous solution, and continue stirring for 15 minutes until the surfactant and wafer abrasive B1 are fully in contact; continue stirring and add 1 part of comb-shaped PAA-PEO (a dispersant) and sodium nitrate, and continue stirring for 15 minutes to form a stable dispersion system solution; then, add 1 part of ethylenediaminetetraacetic acid (EDTA) (a chelating agent) to the stable dispersion system solution, and stir for 15 minutes to obtain a solution without a boundary layer; finally, add potassium hydroxide (a pH adjuster) to the solution without a boundary layer to adjust the pH to an alkaline range of 13.0~13.5, thus obtaining the polishing slurry provided in this embodiment.

[0160] Example 4:

[0161] This embodiment provides a method for preparing a polishing slurry: First, weigh 50 parts of deionized water, add 0.1 parts of the surfactant polyoxyethylene sulfonate to the deionized water, and stir to form a homogeneous solution; then, under continuous stirring, add 1 part of wafer abrasive B2 to the homogeneous solution, and continue stirring for 10 minutes until the surfactant and wafer abrasive B2 are fully in contact; continue stirring and add 1 part of dispersant comb-shaped PAA-PEO and sodium nitrate, and continue stirring for 10 minutes to form a stable dispersion system solution; then, add 0.5 parts of the chelating agent ethylenediaminetetraacetic acid to the stable dispersion system solution, and stir for 10 minutes to obtain a solution without a boundary layer; finally, add potassium bicarbonate as a pH adjuster to the solution without a boundary layer, and adjust the pH to an alkaline range of 12.0~13.0 to obtain the polishing slurry provided in this embodiment.

[0162] Example 5:

[0163] This embodiment provides a method for preparing a polishing slurry: First, weigh 80 parts of deionized water, add 1 part of sodium polyoxyethylene sulfate (POS) surfactant to the deionized water, and stir to form a homogeneous solution; then, under continuous stirring, add 8 parts of wafer abrasive B2 to the homogeneous solution, and continue stirring for 20 minutes until the surfactant and wafer abrasive B2 are fully in contact; continue stirring and add 10 parts of comb-shaped PAA-PEO dispersant and sodium oxalate, and continue stirring for 20 minutes to form a stable dispersion system solution; then, add 5 parts of sodium tartrate chelating agent to the stable dispersion system solution, and stir for 20 minutes to obtain a solution without a boundary layer; finally, add ammonia water as a pH adjuster to the solution without a boundary layer, and adjust the pH to an alkaline range of 7.0~10.0 to obtain the polishing slurry provided in this embodiment.

[0164] Example 6:

[0165] This embodiment provides a method for preparing a polishing slurry: First, weigh 60 parts of deionized water, add 5 parts of sodium dodecylbenzenesulfonate (a surfactant) to the deionized water, and stir to form a homogeneous solution; then, under continuous stirring, add 20 parts of wafer abrasive B3 to the homogeneous solution, and continue stirring for 30 minutes until the surfactant and wafer abrasive B3 are fully in contact; continue stirring and add 5 parts of comb-shaped PAA-PEO (a dispersant) and sodium oxalate, and continue stirring for 30 minutes to form a stable dispersion system solution; then, add 5 parts of sodium tartrate (a chelating agent) to the stable dispersion system solution, and stir for 30 minutes to obtain a solution without a boundary layer; finally, add potassium carbonate (a pH adjuster) to the solution without a boundary layer to adjust the pH to an alkaline range of 10.0~12.0, thus obtaining the polishing slurry provided in this embodiment.

[0166] Example 7:

[0167] This embodiment provides a method for preparing a polishing slurry: First, weigh 80 parts of deionized water, add 1 part of sodium polyoxyethylene sulfate (SO4) surfactant to the deionized water, and stir to form a homogeneous solution; then, under continuous stirring, add 40 parts of wafer abrasive B3 to the homogeneous solution, and continue stirring for 30 minutes until the surfactant and wafer abrasive B3 are fully in contact; continue stirring and add 10 parts of comb-shaped PAA-PEO dispersant and sodium hexametaphosphate, and continue stirring for 30 minutes to form a stable dispersion system solution; then, add 1 part of sorbitol chelating agent to the stable dispersion system solution, and stir for 30 minutes to obtain a solution without a boundary layer; finally, add potassium hydroxide pH adjuster to the solution without a boundary layer, and adjust the pH to an alkaline range of 13.0~13.5 to obtain the polishing slurry provided in this embodiment.

[0168] Example 8:

[0169] This embodiment provides a method for preparing a polishing slurry: First, weigh 50 parts of deionized water, add 5 parts of sodium polyoxyethylene sulfate (SO4) as a surfactant to the deionized water, and stir to form a homogeneous solution; then, under continuous stirring, add 60 parts of wafer abrasive B3 to the homogeneous solution, and continue stirring for 30 minutes until the surfactant and wafer abrasive B3 are fully in contact; continue stirring and add 2 parts of comb-shaped PAA-PEO and sodium hexametaphosphate (HPP) as dispersants, and continue stirring for 30 minutes to form a stable dispersion system solution; then, add 2 parts of sorbitol (SAP) as a chelating agent to the stable dispersion system solution, and stir for 30 minutes to obtain a solution without a boundary layer; finally, add potassium hydroxide (KOH) as a pH adjuster to the solution without a boundary layer, and adjust the pH to an alkaline range of 13.0~13.5 to obtain the polishing slurry provided in this embodiment.

[0170] Table 1 shows the comparison data of the polishing effects of the polishing fluids provided in Examples 3-8.

[0171] Table 1: Comparison of polishing effects of the polishing slurries provided in Examples 3-8

[0172] Example wafer abrasive surfactants dispersant Chelating agents pH adjuster Deionized water Removal rate (%) Unit removal cost (%) 3 1 0.01 30 1 0.5 97 +3 -3000 4 1 0.1 1 0.5 0.1 50 +2 -5000 5 8 1 10 5 7 80 +5 -2000 6 20 5 5 5 15 60 +15 -1500 7 40 1 10 1 29 80 +25 -500 8 60 5 2 2 30 50 +30 -5

[0173] As can be seen from the data in the table above, the polishing slurry prepared using the wafer abrasive according to the technical solution of this application significantly improves the product removal rate: even in polishing slurry formulations using a smaller amount of wafer abrasive, the removal rate is improved by at least 3% compared to existing alumina abrasives, and the improvement in product removal rate becomes more significant as the proportion of wafer abrasive increases. Correspondingly, the unit removal consumption is reduced more significantly in polishing slurry formulations with a smaller proportion of wafer abrasive, reaching up to 3000%, and the reduction rate of unit removal consumption decreases as the proportion of wafer abrasive increases. In the polishing slurry formulation provided in this application, by adjusting the proportion of wafer abrasive and the ratio of other various additives, a high-efficiency polishing slurry with a removal rate improvement of 3%~30% and a unit removal consumption reduction of 5%~3000% can be obtained, which is a significant performance improvement based on the performance of existing polishing slurries.

[0174] It is understood that the amount of the pH adjuster used is closely related to the pH value of the selected pH adjuster. The pH adjustment method provided in the above embodiments is based on adjusting to the preset pH value, and the specific amount used is not a strict limitation on the component ratio of the corresponding embodiments.

[0175] This application also provides the application of the wafer abrasive disclosed in Embodiment 1 or the polishing slurry disclosed in Embodiments 2-8 in sapphire processing. The wafer abrasive and polishing slurry disclosed in this application are not only suitable for polishing various types of plates or sheets, but are particularly suitable for the polishing process of sapphire wafers: due to the organic modification of the silicon carbide micropowder surface to form a special core-shell structure abrasive, combined with the hydrated thin layer generated during the polishing process of sapphire wafers, the interaction between the two further enhances the removal capacity of the wafer abrasive itself. Therefore, this wafer abrasive has a superior effect in the polishing process of sapphire products. Furthermore, during the polishing process of sapphire wafers, the wafer abrasive provided in this application has self-healing and recyclable characteristics. The actual wear rate of the wafer abrasive is 0.5%~5%, significantly reducing the wafer wear rate and effectively reducing the cost of polishing consumables.

[0176] In summary, the wafer abrasive, polishing slurry, preparation method, and application provided in this application effectively overcome the various shortcomings of the prior art and have high industrial application value.

[0177] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A method for preparing a wafer abrasive, characterized in that, Includes the following steps: Silicon carbide micro powder is provided; Silicon carbide micro powder was impregnated in dihalosilane, and intermediate A1 with polydimethylsilane coated on the surface of silicon carbide micro powder was obtained by polymer impregnation pyrolysis method. Intermediate A1 undergoes a rearrangement reaction under high temperature conditions to obtain intermediate A2, which is coated with polycarbosilane on the surface of silicon carbide micropowder. Heating intermediate A2 causes it to undergo a substitution reaction with hydrogen halide under the action of a catalyst, yielding intermediate A3 with halogenated polycarbosilane coated on the surface of silicon carbide micropowder. When intermediate A3 is heated in an alkaline environment, the halopolycarbosilane in its outer shell layer hydrolyzes into hydroxypolycarbosilane, resulting in a silicon carbide core-shell abrasive B1 coated with hydroxypolycarbosilane.

2. The method for preparing wafer abrasive according to claim 1, characterized in that, After obtaining wafer abrasive B1 with a core-shell structure of silicon carbide coated with hydroxyl polycarbosilane, wafer abrasive B1 is heated to cause it to decompose, resulting in wafer abrasive B2 with a core-shell structure of hydroxyl radicals.

3. The method for preparing wafer abrasive according to claim 2, characterized in that, During the pyrolysis of wafer abrasive B1, hydroxyl polycarbosilane near the core layer of silicon carbide micropowder simultaneously generates silicon carbide, resulting in a cross-linked structural layer formed by silicon carbide and some thermally pyrolyzed polycarbosilane.

4. The method for preparing wafer abrasive according to claim 1, characterized in that, After obtaining a core-shell structured wafer abrasive B1 with hydroxyl polycarbosilane-coated silicon carbide, the wafer abrasive B1 was oxidized under chromium trioxide and acetic acid conditions to obtain a core-shell structured wafer abrasive B3 with carboxyl polycarbosilane-coated silicon carbide.

5. The method for preparing wafer abrasive according to claim 4, characterized in that, The wafer abrasive B3 is heated to cause it to decompose, and the carboxyl polycarbosilane near the core layer of silicon carbide micro powder is converted into silicon carbide, resulting in a cross-linked structural layer formed by silicon carbide and some thermally decomposed polycarbosilane.

6. A wafer abrasive, characterized in that, The wafer abrasive is prepared using the method described in claim 3 or 5, and the wafer abrasive has a core-shell structure, wherein the core-shell structure includes at least a core layer and an outer shell layer covering the surface of the core layer, wherein... The core layer is made of silicon carbide micro powder; The outer shell is made of hyperbranched polycarbosilane with hydrophilic groups.

7. The wafer abrasive according to claim 6, characterized in that, The hydrophilic group is a hydroxyl or a carboxyl group.

8. The wafer abrasive according to claim 6, characterized in that, The average particle size D50 of the silicon carbide micro powder is 0.5-2.5 μm; The Mohs hardness of the silicon carbide micro powder is 9.2~9.

5.

9. The wafer abrasive according to claim 6, characterized in that, There is also an intermediate layer between the core layer and the outer shell layer, which is a cross-linked structure layer formed by silicon carbide and partially thermally decomposed polycarbosilane.

10. A polishing liquid, characterized in that, The polishing slurry is composed of the following components in parts by weight: 1 to 60 parts of the wafer abrasive as described in any one of claims 6 to 9; Surfactant, 0.01~5 parts; Dispersant, 1-30 parts; Chelating agent, 0.01~5 parts; pH adjuster, 0.1~30 parts; Deionized water, 50-97 parts.

11. The polishing slurry according to claim 10, characterized in that, The surfactant is a water-soluble reagent with sulfonic acid groups.

12. The polishing slurry according to claim 10, characterized in that, The surfactant includes one or more of sodium dodecylbenzenesulfonate, sodium polyoxyethylene sulfate, or polyoxyethylene sulfonate.

13. The polishing slurry according to claim 10, characterized in that, The dispersant comprises a hyperbranched hydrophilic polymer.

14. The polishing slurry according to claim 13, characterized in that, The dispersant also includes one or more of sodium nitrate, sodium oxalate, sodium hexametaphosphate, sodium pyrophosphate, or sodium tripolyphosphate.

15. The polishing slurry according to claim 10, characterized in that, The chelating agent is a polyol and / or a polycarboxylic acid.

16. The polishing slurry according to claim 10, characterized in that, The chelating agent includes one or more of ethylenediaminetetraacetic acid, sodium tartrate, or sorbitol.

17. The polishing slurry according to claim 10, characterized in that, The pH range of the polishing solution is 7-14.

18. The polishing slurry according to claim 17, characterized in that, The pH adjuster includes one or more of potassium hydroxide, ammonia, potassium / sodium carbonate, potassium / sodium bicarbonate, sodium / potassium hexametaphosphate, sodium lauryl ester, and sodium oxalate.

19. A method for preparing a polishing slurry, characterized in that, Includes the following steps: Add a surfactant to deionized water and stir to form a homogeneous solution; Under stirring conditions, the wafer abrasive as described in any one of claims 6 to 9 is added to the homogeneous solution, and stirring is continued until the surfactant is in full contact with the wafer abrasive; Under stirring conditions, continue adding the dispersant and continue stirring to form a stable dispersion solution; A chelating agent was added to the stable dispersion system solution, and the mixture was stirred to obtain a solution without a boundary layer. A pH adjuster is added to the solution without a boundary layer to adjust the pH to an alkaline range of 7-14, thus obtaining a polishing solution.

20. The application of a wafer abrasive as described in any one of claims 6 to 9 or a polishing slurry as described in any one of claims 10 to 18 in sapphire processing.

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