Acid aluminum oxide polishing composition for rough polishing of silicon carbide substrate and polishing method

Abstract

The invention discloses an acidic aluminum oxide polishing composition for rough polishing of a silicon carbide substrate and a polishing method. The polishing composition comprises an aluminum oxide abrasive, a dispersing agent, a suspending agent, a pH regulator and water, wherein the suspending agent is selected from at least one of chitosan loaded sulfonated metal phthalocyanine, cellulose loaded sulfonated metal phthalocyanine, chitin loaded sulfonated metal phthalocyanine, chitosan loaded artemisinin or cellulose loaded artemisinin. Under the auxiliary action of ultraviolet light, chitosan loads sulfonated metal phthalocyanine, cellulose loads sulfonated metal phthalocyanine, chitin loads sulfonated metal phthalocyanine, chitosan loads artemisinin or cellulose loads artemisinin to form hydroxyl free radicals. OH or generate active oxygen, the active oxygen and a silicon carbide substrate are subjected to an oxidation reaction, and a soft surface modification layer is generated; therefore, the surface hardness is reduced, high-speed and high-quality polishing of the Si surface and the C surface of the silicon carbide substrate can be realized, and the surface roughness of the polished silicon carbide substrate is extremely low.

Description

Technical Field

[0001] The invention relates to the field of substrate surface treatment, and in particular to an acidic aluminum oxide polishing composition for rough polishing of a silicon carbide substrate and a polishing method. Background Art

[0002] Silicon carbide (SiC) is a wide bandgap semiconductor material that has attracted much attention due to its good thermal conductivity, high temperature resistance, high breakdown field, high saturated electron drift velocity and strong radiation resistance. With the advent of the 5G era, as the demand for electronic products such as smart cars, smart refrigerators, and smart phones has soared, silicon carbide substrates as the third-generation semiconductors have also gradually increased. In the manufacturing and epitaxial growth of the next generation of power devices, there are strict requirements for the final surface quality control of silicon carbide single crystal materials. Atomic-level flatness, damage-free and defect-free silicon carbide substrates are crucial. Any micro-defects on the substrate surface may affect the growth results of the epitaxial layer.

[0003] At present, chemical mechanical polishing (CMP) is one of the most effective technical methods to achieve global flattening. However, the ultra-high mechanical hardness and ultra-strong chemical inertness make it difficult for SiC substrates to achieve high removal rates and atomic-level flat surfaces. Currently, ultra-precision polishing of silicon carbide substrates mostly uses chemical mechanical polishing technology that effectively combines surface chemical modification and soft abrasive polishing. CMP technology first uses chemical reactions to modify the surface of silicon carbide substrates to reduce their surface hardness, and then uses the mechanical friction between soft abrasives and the modified layer on the substrate surface to remove the modified layer. Through the continuous alternation of chemical and mechanical actions, the silicon carbide substrate is finally polished to obtain a high-quality surface.

[0004] Specifically, the CMP process in the manufacturing process of silicon carbide substrates is mainly divided into rough polishing and fine polishing. The rough polishing process has a faster polishing rate, but due to the strong oxidizing property of strongly acidic potassium permanganate, the surface corrosion of the silicon carbide substrate after polishing is serious, and there are a large number of scratches on the C surface when working with a hard pad, which requires fine polishing repair. However, the alkaline polishing composition currently used in fine polishing has a too slow rate, and it takes a very long time to remove the scratches and surface defects left by the rough polishing. The polishing time is about 1-2 hours, and the polishing cost is too high, which is not suitable for mass production of silicon carbide substrates.

[0005] In summary, it can be seen that in the art, when polishing a substrate, there are still problems such as low polishing efficiency and easy occurrence of surface defects after polishing. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide an acidic aluminum oxide polishing composition and a polishing method for rough polishing of silicon carbide substrates, so as to solve the problems of low polishing efficiency and easy occurrence of surface defects after polishing when polishing silicon carbide substrates.

[0007] In order to achieve the above invention object, the present invention adopts the following technical scheme:

[0008] An acidic alumina polishing composition for rough polishing of a silicon carbide substrate, the composition comprising an alumina abrasive, a dispersant, a suspending agent, a pH regulator and water; wherein the suspending agent is selected from at least one of chitosan-supported sulfonated metal phthalocyanine, cellulose-supported sulfonated metal phthalocyanine, chitin-supported sulfonated metal phthalocyanine, chitosan-supported artemisinin or cellulose-supported artemisinin, and the mass ratio of the chitosan, cellulose or chitosan to the sulfonated metal phthalocyanine or artemisinin is 0.2:1-0.7:1;

[0009] The pH value of the polishing composition is 2-6.

[0010] Preferably, the polishing composition comprises, by mass percentage, 5-15% of aluminum oxide abrasive, 1-5% of dispersant, 1-5% of suspending agent, 1-5% of pH regulator, and the balance is water.

[0011] Preferably, the particle size of the aluminum oxide abrasive is 100-1000 nm, preferably 100-300 nm, and more preferably 100, 200 or 300 nm.

[0012] Preferably, the sulfonated metal phthalocyanine is selected from sulfonated copper phthalocyanine, sulfonated zinc phthalocyanine or sulfonated cobalt phthalocyanine.

[0013] Preferably, the suspending agent is selected from at least one of chitosan-supported sulfonated metal phthalocyanine, cellulose-supported sulfonated metal phthalocyanine, and chitin-supported sulfonated metal phthalocyanine.

[0014] Further preferably, the suspending agent is selected from at least one of chitosan-supported sulfonated copper phthalocyanine, cellulose-supported sulfonated copper phthalocyanine, chitin-supported sulfonated copper phthalocyanine or chitosan-supported sulfonated cobalt phthalocyanine.

[0015] Preferably, the mass ratio of chitosan, cellulose or chitin to sulfonated metal phthalocyanine or artemisinin is 0.2:1-0.5:1.

[0016] Preferably, the dispersant is selected from at least one of polyethylene glycol, polypropylene glycol, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate or sodium dodecyl sulfate.

[0017] Preferably, the pH adjuster is selected from at least one of citric acid, formic acid, acetic acid, nitric acid, aluminum nitrate, sulfuric acid or glycine, and the pH adjuster is preferably aluminum nitrate.

[0018] Another aspect of the present invention is to provide a substrate polishing method, the substrate polishing method comprising:

[0019] The polishing composition is used for mechanical chemical grinding, and the mechanical chemical grinding is assisted by ultraviolet light irradiation.

[0020] Preferably, the wavelength of the ultraviolet light used in the mechanochemical polishing is 250-420 nm.

[0021] Preferably, the power of the ultraviolet light used in the mechanochemical polishing is 10-100 mW.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The polishing composition of the invention is selected from chitosan-supported sulfonated metal phthalocyanine, cellulose-supported sulfonated metal phthalocyanine, chitin-supported sulfonated metal phthalocyanine, chitosan-supported artemisinin or cellulose-supported artemisinin as a suspending agent. Under the auxiliary action of ultraviolet light, hydroxyl radicals OH or active oxygen generated by the chitosan-supported sulfonated metal phthalocyanine, cellulose-supported sulfonated metal phthalocyanine, chitin-supported sulfonated metal phthalocyanine, chitosan-supported artemisinin or cellulose-supported artemisinin undergo oxidation reaction with the silicon carbide substrate to generate a softer surface modification layer, thereby reducing the surface hardness, and realizing high-speed and high-quality polishing of the Si surface and the C surface of the silicon carbide substrate. After polishing, the surface roughness of the silicon carbide substrate is extremely low. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a UV-assisted chemical mechanical polishing device provided in Application Example 1;

[0025] Among them, 1-polishing head, 2-control system, 3-polishing disk, 4-ultraviolet light source, 5-polishing composition, 6-polishing pad, 7-silicon carbide substrate to be polished. DETAILED DESCRIPTION

[0026] Below in conjunction with the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described. Obviously, the described embodiment is only a part of the embodiment of the present invention, rather than all the embodiments. If specific conditions are not specified in the embodiment, it is carried out according to the conditions recommended by normal conditions or manufacturers. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0027] The invention provides an acidic aluminum oxide polishing composition for rough polishing of a silicon carbide substrate. The polishing composition comprises an aluminum oxide abrasive, a dispersant, a suspending agent, a pH regulator and water; wherein the suspending agent is selected from at least one of chitosan-supported sulfonated metal phthalocyanine, cellulose-supported sulfonated metal phthalocyanine, chitin-supported sulfonated metal phthalocyanine, chitosan-supported artemisinin or cellulose-supported artemisinin, and the mass ratio of the chitosan, cellulose or chitosan to the sulfonated metal phthalocyanine or artemisinin is 0.2:1-0.7:1.

[0028] Wherein, due to the viscosity of chitosan, cellulose and chitosan and the richness of a large number of groups, the suspending agent is in the form of a gel in the polishing composition, and can be used as a suspending agent in the polishing composition, so that the polishing composition has excellent suspension dispersibility and stability. In addition, chitosan, cellulose and chitosan are easy to generate hydroxyl radicals under conditions such as ultraviolet light, high temperature or chemical oxidants. The present invention mainly causes chitosan, cellulose and chitosan to lose a hydrogen atom to form hydroxyl radicals OH under the auxiliary action of ultraviolet light. The hydroxyl radicals OH formed subsequently react with the silicon carbide substrate to generate a softer surface modification layer, thereby reducing the surface hardness and improving the polishing rate.

[0029] In addition, the suspending agent contains the structure of soluble sulfonated metal phthalocyanine, which is a highly efficient photosensitizer. Under ultraviolet light irradiation, the sulfonated metal phthalocyanine can generate active oxygen (such as OH free radicals) through photogenerated electron-hole pairs, and undergo oxidation reaction with the silicon carbide substrate to generate a softer surface modification layer, thereby reducing the surface hardness and improving the polishing rate; at the same time, after the sulfonic acid group is added, its solubility in water can be effectively enhanced, the relative concentration can be increased, and the photocatalytic ability can be improved.

[0030] In addition, the molecular structure of artemisinin contains active groups such as peroxide, acetal, ketal, and lactone. After artemisinin crystals are irradiated with ultraviolet light, the peroxide bonds in them break to form hydroxyl radicals OH, which react with the silicon carbide substrate to form a surface modification layer, thereby reducing the surface hardness and increasing the polishing rate.

[0031] Therefore, the acidic alumina polishing composition for rough polishing of a silicon carbide substrate of the present invention does not require additional addition of an oxidizing agent.

[0032] In an embodiment of the present invention, the sulfonated metal phthalocyanine is preferably at least one of sulfonated copper phthalocyanine, sulfonated zinc phthalocyanine or sulfonated cobalt phthalocyanine.

[0033] The suspending agent is preferably selected from at least one of chitosan-supported sulfonated metal phthalocyanine, cellulose-supported sulfonated metal phthalocyanine, or chitin-supported sulfonated metal phthalocyanine. The possible reason is that the metal phthalocyanine has a stable structure, and its water solubility is enhanced after sulfonation, so it can be evenly dispersed in the polishing composition and continuously catalyze the oxidation reaction. Moreover, the supported metal phthalocyanine not only acts as a photocatalyst, but also may be embedded in the polishing pad as an abrasive, thereby improving the removal efficiency through the dual effects of oxidation softening and mechanical grinding.

[0034] In an embodiment of the present invention, the suspending agent is selected from at least one of chitosan-supported sulfonated copper phthalocyanine, cellulose-supported sulfonated copper phthalocyanine, chitin-supported sulfonated copper phthalocyanine, or chitosan-supported sulfonated cobalt phthalocyanine. The possible reason is that due to the photocatalytic activity of metal phthalocyanines: Cu>Co>Zn, under ultraviolet light excitation, copper phthalocyanine produces more efficient active oxygen than cobalt phthalocyanine, and cobalt phthalocyanine produces more efficient active oxygen than zinc phthalocyanine. The ·OH catalyzed by copper phthalocyanine preferentially attacks the Si site on the SiC surface to generate uniform SiO 2 In addition, the complex formed by sulfonated copper phthalocyanine and sulfonated cobalt phthalocyanine on chitosan has better dispersion and uniformity, and may promote chemical reactions on the surface of the material by generating more active free radicals during the polishing process. These active free radicals can more effectively remove impurities and defects on the surface, thereby improving the polishing quality.

[0035] In the embodiment of the present invention, the polishing composition includes, by mass percentage, 5-15% of aluminum oxide abrasive particles, 1-5% of a dispersant, 1-5% of a suspending agent, 1-5% of a pH regulator, and the balance is water.

[0036] The aluminum oxide abrasive in the present invention is selected from α-Al 2 O 3 The particle size of the aluminum oxide powder is 100nm-1000nm, and preferably, the particle size of the aluminum oxide powder is 100-300nm. The amount of aluminum oxide abrasive added is generally 1wt%-20wt% of the total mass of the polishing composition. Preferably, for the sake of higher polishing rate, lower defects and better storage stability, the amount of aluminum oxide abrasive particles added is 5wt%-15wt% of the total amount of the polishing composition.

[0037] The polishing composition of the present invention may contain one or more dispersants. The dispersant can prevent the nano-scale aluminum oxide from agglomerating easily, improve its dispersibility, and prevent agglomeration. Conventional dispersants can be used. Dispersants include, but are not limited to, at least one of polyethylene glycol, polyglycerol, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and sodium dodecyl sulfate. Preferably, the dispersant is at least one of sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and sodium dodecyl sulfate.

[0038] The dispersant may be included in the chemical mechanical polishing composition in conventional amounts, preferably in an amount of 0.1 wt% to 10 wt%, preferably 1 wt% to 5 wt% of the polishing composition.

[0039] The polishing composition of the present invention contains one or more of the above-mentioned suspending agents, and may contain 0.1wt%-10wt% of the suspending agent. Preferably, for the sake of higher polishing rate, lower defects and better storage stability, the amount of the suspending agent added is 1wt%-5wt% of the total amount of the polishing composition.

[0040] The polishing composition of the present invention may further comprise one or more conventional suspending agents, including but not limited to at least one of carboxymethyl cellulose, sodium polyacrylate, polyacrylamide, xanthan gum, hydroxypropyl methyl cellulose or methyl cellulose.

[0041] The polishing composition of the present invention may contain one or more pH adjusters. The pH adjuster is at least one of citric acid, formic acid, acetic acid, nitric acid, aluminum nitrate, sulfuric acid or glycine, wherein aluminum nitrate is preferably used as the pH adjuster, which is convenient for improving the stability of the pH value during the polishing process, thereby greatly improving the stability of the polishing. The amount of the pH adjuster added is 1wt%-5wt% of the total amount of the polishing composition; the pH value of the polishing composition is adjusted to the range of 2-6.

[0042] The polishing composition of the present invention further comprises water. Preferably, the water contained in the chemical mechanical polishing composition is at least one of deionized water and distilled water to limit incidental impurities.

[0043] The invention provides a method for preparing an acidic aluminum oxide polishing composition for rough polishing of a silicon carbide substrate. The method comprises: mixing aluminum oxide powder and part of a solvent; then mixing a dispersant, a suspending agent and the remaining solvent; and adjusting the pH value and stirring to obtain the polishing composition.

[0044] The present invention provides a polishing method using the polishing composition described above, wherein the polishing method comprises performing ultraviolet catalytic assisted chemical mechanical polishing on the surface of a silicon carbide substrate, specifically comprising the following steps:

[0045] (1) Fixing the silicon carbide substrate to be polished in a polishing head and applying pressure on the back side of the polishing head;

[0046] (2) contacting the silicon carbide substrate in the polishing head with the polishing pad and performing rotational and translational motions, while transporting the polishing composition from the polishing pad to the surface of the silicon carbide substrate;

[0047] (3) The polishing composition is irradiated with ultraviolet light, and a photocatalytic reaction occurs on the surface of the silicon carbide substrate under the action of a photocatalyst, thereby achieving ultraviolet-assisted chemical mechanical polishing.

[0048] The polishing method provided by the present invention adopts chemical mechanical polishing assisted by ultraviolet light catalysis. During the polishing process, an ultraviolet light generator is used to irradiate chitosan-loaded sulfonated metal phthalocyanine, cellulose-loaded sulfonated metal phthalocyanine, chitin-loaded sulfonated metal phthalocyanine, chitosan-loaded artemisinin or cellulose-loaded artemisinin in the polishing composition to cause a photocatalytic reaction to occur, thereby generating more hydroxyl radicals, thereby improving the removal rate of the silicon carbide substrate.

[0049] As a preferred technical solution of the present invention, the pressure applied in step (1) is 1-10psi, for example, it can be 1psi, 2psi, 3psi, 4psi, 5psi, 6psi, 7psi, 8psi, 9psi or 10psi, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0050] Preferably, the rotation speed of the polishing head in step (2) is 20-120 rpm, for example, it can be 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, 80 rpm, 90 rpm, 100 rpm or 110 rpm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0051] Preferably, the polishing pad in step (2) is made of polyurethane or non-woven fabric, preferably polyurethane.

[0052] Preferably, the flow rate of the polishing composition in step (2) is 50-300 mL / min, for example, 70 mL / min, 100 mL / min, 120 mL / min, 140 mL / min, 150 mL / min, 200 mL / min, 250 mL / min or 280 mL / min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0053] Preferably, the power of the ultraviolet light used in the mechanochemical polishing in step (3) is 10-100 mW, for example, it can be 10 mW, 20 mW, 30 mW, 40 mW, 50 mW, 60 mW, 70 mW, 80 mW, 90 mW or 100 mW, but is not limited to the listed values, and other values ​​not listed within this range also meet the requirements.

[0054] Preferably, the wavelength of the ultraviolet light in step (3) is 250-420 nm, for example, it can be 270 nm, 300 nm, 320 nm, 350 nm, 380 nm, 400 nm or 410 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0055] Preferably, the polishing time is 30-120 min, for example, it can be 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] In the present invention, a one-step polishing method (chemical mechanical polishing assisted by ultraviolet light catalysis) is used for the polishing process of the silicon carbide substrate, and by controlling parameters such as polishing pressure, polishing composition flow, polishing speed, and polishing time during the polishing process, the polishing mode of rough polishing + fine polishing of the traditional polishing process is simplified, the polishing process steps are shortened, the polishing efficiency is improved, and the mass production needs can be better met.

[0057] The above and other advantages of the present invention may be better understood through the following examples, but the following examples are not intended to limit the scope of the present invention.

[0058] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0059] <Preparation of chitosan-supported sulfonated copper phthalocyanine A1>

[0060] (1) Pretreatment of chitosan: 50 g of chitosan was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 h to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 h.

[0061] (2) Loading process: Sulfonated copper phthalocyanine was dissolved in ultrapure water to prepare a 4% sulfonated copper phthalocyanine solution; then mixed with the above-mentioned pretreated chitosan, wherein the mass ratio of chitosan to sulfonated copper phthalocyanine was 0.3:1, stirred at room temperature for 18 hours, and loaded by hydrogen bonding and electrostatic adsorption;

[0062] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain chitosan-loaded sulfonated copper phthalocyanine A1.

[0063] <Preparation of chitosan-supported sulfonated copper phthalocyanine A2>

[0064] (1) Pretreatment of chitosan: 50 g of chitosan was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 h to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 h.

[0065] (2) Loading process: dissolving sulfonated copper phthalocyanine in ultrapure water to prepare a 4% sulfonated copper phthalocyanine solution; then mixing with the above-mentioned pretreated chitosan, wherein the mass ratio of chitosan to sulfonated copper phthalocyanine is 0.2:1, stirring at room temperature for 18 hours, and achieving loading through hydrogen bonding and electrostatic adsorption;

[0066] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain chitosan-loaded sulfonated copper phthalocyanine A2.

[0067] <Preparation of chitosan-supported sulfonated copper phthalocyanine A3>

[0068] (1) Pretreatment of chitosan: 50 g of chitosan was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 h to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 h.

[0069] (2) Loading process: dissolving sulfonated copper phthalocyanine in ultrapure water to prepare a 4% sulfonated copper phthalocyanine solution; then mixing with the above-mentioned pretreated chitosan, wherein the mass ratio of chitosan to sulfonated copper phthalocyanine is 0.5:1, stirring at room temperature for 18 hours, and achieving loading through hydrogen bonding and electrostatic adsorption;

[0070] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain chitosan-loaded sulfonated copper phthalocyanine A3.

[0071] <Preparation of chitosan-supported sulfonated copper phthalocyanine A4>

[0072] (1) Pretreatment of chitosan: 50 g of chitosan was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 h to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 h.

[0073] (2) Loading process: Sulfonated copper phthalocyanine was dissolved in ultrapure water to prepare a 4% sulfonated copper phthalocyanine solution; then mixed with the pretreated chitosan, wherein the mass ratio of chitosan to sulfonated copper phthalocyanine was 0.7:1, stirred at room temperature for 18 hours, and loaded by hydrogen bonding and electrostatic adsorption;

[0074] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain chitosan-loaded sulfonated copper phthalocyanine A4.

[0075] <Preparation of chitosan-supported sulfonated zinc phthalocyanine B1>

[0076] (1) Pretreatment of chitosan: 50 g of chitosan was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 h to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 h.

[0077] (2) Loading process: dissolving sulfonated zinc phthalocyanine in ultrapure water to prepare a 4% sulfonated zinc phthalocyanine solution; then mixing with the above-mentioned pretreated chitosan, wherein the mass ratio of chitosan to sulfonated zinc phthalocyanine is 0.3:1, stirring at room temperature for 18 hours, and achieving loading through hydrogen bonding and electrostatic adsorption;

[0078] (3) Post-treatment of the product: The loaded product of the above step (2) is filtered and washed, and dried at 60° C. for 6 h to obtain chitosan-loaded sulfonated zinc phthalocyanine.

[0079] <Preparation of chitosan-supported sulfonated cobalt phthalocyanine C1>

[0080] (1) Pretreatment of chitosan: 50 g of chitosan was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 h to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 h.

[0081] (2) Loading process: dissolving sulfonated cobalt phthalocyanine in ultrapure water to prepare a 4% sulfonated cobalt phthalocyanine solution; then mixing with the above-mentioned pretreated chitosan, wherein the mass ratio of chitosan to sulfonated cobalt phthalocyanine is 0.3:1, stirring at room temperature for 18 hours, and achieving loading through hydrogen bonding and electrostatic adsorption;

[0082] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain chitosan-loaded sulfonated cobalt phthalocyanine C1.

[0083] <Preparation of cellulose-supported sulfonated copper phthalocyanine D1>

[0084] (1) Pretreatment of microcrystalline cellulose: 50 g of microcrystalline cellulose was soaked in 500 ml of 10% NaOH solution at 60° C. for 2 hours to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 hours;

[0085] (2) Loading process: Sulfonated copper phthalocyanine was dissolved in ultrapure water to prepare a 4% sulfonated copper phthalocyanine solution; then mixed with the above-mentioned pretreated cellulose, wherein the mass ratio of cellulose to sulfonated copper phthalocyanine was 0.3:1, stirred at room temperature for 18 hours, and loaded by hydrogen bonding and electrostatic adsorption;

[0086] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain cellulose-loaded sulfonated copper phthalocyanine D1.

[0087] <Preparation of cellulose-supported sulfonated copper phthalocyanine D2>

[0088] (1) Pretreatment of microcrystalline cellulose: 50 g of microcrystalline cellulose was soaked in 500 ml of 10% NaOH solution at 60° C. for 2 hours to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 hours;

[0089] (2) Loading process: Sulfonated copper phthalocyanine was dissolved in ultrapure water to prepare a 4% sulfonated copper phthalocyanine solution; then mixed with the above-mentioned pretreated cellulose, wherein the mass ratio of cellulose to sulfonated copper phthalocyanine was 0.4:1, stirred at room temperature for 18 hours, and loaded by hydrogen bonding and electrostatic adsorption;

[0090] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain cellulose-loaded sulfonated copper phthalocyanine D2.

[0091] <Preparation of cellulose-supported sulfonated zinc phthalocyanine E1>

[0092] (1) Pretreatment of microcrystalline cellulose: 50 g of microcrystalline cellulose was soaked in 500 ml of 10% NaOH solution at 60° C. for 2 hours to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 hours;

[0093] (2) Loading process: dissolving sulfonated zinc phthalocyanine in ultrapure water to prepare a 4% sulfonated zinc phthalocyanine solution; then mixing it with the above-mentioned pretreated cellulose, wherein the mass ratio of cellulose to sulfonated zinc phthalocyanine is 0.3:1, stirring at room temperature for 18 hours, and achieving loading through hydrogen bonding and electrostatic adsorption;

[0094] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain cellulose-loaded sulfonated zinc phthalocyanine E1.

[0095] <Preparation of cellulose-supported sulfonated cobalt phthalocyanine F1>

[0096] (1) Pretreatment of microcrystalline cellulose: 50 g of microcrystalline cellulose was soaked in 500 ml of 10% NaOH solution at 60° C. for 2 hours to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 hours;

[0097] (2) Loading process: dissolving sulfonated cobalt phthalocyanine in ultrapure water to prepare a 4% sulfonated cobalt phthalocyanine solution; then mixing it with the above-mentioned pretreated cellulose, wherein the mass ratio of cellulose to sulfonated cobalt phthalocyanine is 0.3:1, stirring at room temperature for 18 hours, and achieving loading through hydrogen bonding and electrostatic adsorption;

[0098] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain cellulose-loaded sulfonated cobalt phthalocyanine F1.

[0099] <Preparation of chitin-supported sulfonated copper phthalocyanine G1>

[0100] (1) Pretreatment of chitin: 50 g of chitin was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 hours to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 hours;

[0101] (2) Loading process: Sulfonated copper phthalocyanine was dissolved in ultrapure water to prepare a 4% sulfonated copper phthalocyanine solution; then mixed with the above-mentioned pretreated chitin, wherein the mass ratio of chitin to sulfonated copper phthalocyanine was 0.3:1, stirred at room temperature for 18 hours, and loaded by hydrogen bonding and electrostatic adsorption;

[0102] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain chitin-loaded sulfonated copper phthalocyanine G1.

[0103] <Preparation of chitin-supported sulfonated zinc phthalocyanine H1>

[0104] (1) Pretreatment of chitin: 50 g of chitin was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 hours to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 hours;

[0105] (2) Loading process: dissolving sulfonated zinc phthalocyanine in ultrapure water to prepare a 4% sulfonated zinc phthalocyanine solution; then mixing with the above-mentioned pretreated chitin, wherein the mass ratio of chitin to sulfonated zinc phthalocyanine is 0.3:1, stirring at room temperature for 18 hours, and achieving loading through hydrogen bonding and electrostatic adsorption;

[0106] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain chitin-loaded sulfonated zinc phthalocyanine H1.

[0107] <Preparation of chitin-supported sulfonated cobalt phthalocyanine K1>

[0108] (1) Pretreatment of chitin: 50 g of chitin was immersed in 500 ml of 10% NaOH solution at 60° C. for 2 hours to remove surface impurities and expose hydroxyl active sites, and then dried at 60° C. for 6 hours;

[0109] (2) Loading process: dissolving sulfonated cobalt phthalocyanine in ultrapure water to prepare a 4% sulfonated cobalt phthalocyanine solution; then mixing it with the above-mentioned pretreated chitin, wherein the mass ratio of chitin to sulfonated cobalt phthalocyanine is 0.3:1, stirring at room temperature for 18 hours, and achieving loading through hydrogen bonding and electrostatic adsorption;

[0110] (3) Post-treatment of the product: The loaded product of the above step (2) was filtered and washed, and dried at 60° C. for 6 h to obtain chitin-loaded sulfonated cobalt phthalocyanine K1.

[0111] <Preparation of chitosan-loaded artemisinin S1>

[0112] (1) adding artemisinin into anhydrous ethanol at room temperature to prepare an artemisinin solution with a mass fraction of 10%;

[0113] (2) adding chitosan to acetic acid and stirring at 50° C. for 30 min to prepare a chitosan solution with a mass fraction of 5%;

[0114] (3) The artemisinin solution was slowly added dropwise to a 5% chitosan solution, wherein the mass ratio of chitosan to artemisinin was 0.3:1, and the mixture was stirred for 20 min. The precipitate was filtered and dried at 60° C. for 6 h to obtain chitosan-loaded artemisinin powder S1.

[0115] <Preparation of Cellulose-loaded Artemisinin T1>

[0116] (1) adding artemisinin into anhydrous ethanol at room temperature to prepare an artemisinin solution with a mass fraction of 10%;

[0117] (2) adding cellulose to acetic acid and stirring at 50° C. for 30 min to prepare a cellulose solution with a mass fraction of 5%;

[0118] (3) The artemisinin solution was slowly added dropwise to a cellulose solution having a mass fraction of 5%, wherein the mass ratio of cellulose to artemisinin was 0.3:1, and the mixture was stirred for 20 min. The precipitate was filtered and dried at 60° C. for 6 h to obtain cellulose-loaded artemisinin powder T1.

[0119] <Preparation of chitosan-loaded titanium dioxide>

[0120] (1) adding titanium dioxide into deionized water at room temperature to prepare a titanium dioxide solution with a mass fraction of 10%;

[0121] (2) adding chitosan to acetic acid and stirring at 50° C. for 30 min to prepare a chitosan solution with a mass fraction of 5%;

[0122] (3) Slowly add the above titanium dioxide solution dropwise into a chitosan solution with a mass fraction of 5%, wherein the mass ratio of chitosan to titanium dioxide is 0.3:1, stir for 20 minutes, filter and collect the precipitate, and dry at 60°C for 6 hours to obtain chitosan-loaded titanium dioxide.

[0123] Preparation steps of the polishing composition:

[0124] In terms of mass percentage, 5-15% of aluminum oxide powder is added to 70% of deionized water and stirred for 30 minutes; 1-5% of a dispersant is added and stirred for 30 minutes; 1-5% of a suspending agent is slowly added and stirred for 60 minutes; the remaining deionized water is supplemented, 1-5% of a pH regulator is added, and stirred for 120 minutes to obtain the polishing composition.

[0125] Table 1 is a table of the components of the polishing compositions of Examples 1 to 20 and Comparative Examples 1 to 5

[0126]

[0127] In order to verify the polishing effect of the polishing composition of the present invention, the surface of the silicon carbide substrate was subjected to ultraviolet catalytic assisted chemical mechanical polishing using the polishing compositions of Examples 1 to 20 and Comparative Examples 1 to 5, which specifically includes the following steps:

[0128] (1) A polishing pad (model: Suba 800) is fixed on the surface of a polishing plate, a 6-inch silicon carbide substrate to be polished is fixed in a polishing head, and a pressure of 3 psi is applied to the back of the polishing head;

[0129] (2) The silicon carbide substrate in the polishing head was brought into contact with the polishing pad and rotated (upper plate speed 24 rpm, lower plate speed 30 rpm) and translated, while the polishing composition prepared in the embodiment and the comparative example was transported from the polishing pad to the surface of the silicon carbide substrate at a flow rate of 100 mL / min;

[0130] (3) The polishing composition is irradiated with ultraviolet light having a wavelength of 380 nm and a power of 100 W. Under the action of the suspending agent, a photocatalytic reaction occurs on the surface of the silicon carbide substrate for 2 hours, thereby achieving ultraviolet-assisted chemical mechanical polishing.

[0131] After polishing, the silicon carbide substrate was ultrasonically cleaned with a cleaning solution for 5 minutes and then dried with nitrogen. The removal rate (μm / h) of silicon carbide was obtained from the weight change of the silicon carbide substrate before and after polishing and the polishing time; the substrates in the above embodiments and comparative examples were tested using an atomic force microscope to obtain the roughness of the substrate surface; the total thickness change TTV of the substrate was measured using a TG300LS film thickness measuring instrument. The removal rate RR, surface roughness value Ra and total thickness change TTV after polishing are listed in Table 2.

[0132] Table 2 Polishing effect of polishing composition examples 1 to 20 of the present invention and comparative examples 1 to 5

[0133]

[0134] Combined with Table 2, by comparing Examples 8 to 16 with Comparative Examples 1 to 5, it can be seen that the polishing composition provided by the present invention, because it comprises chitosan-loaded sulfonated metal phthalocyanine, cellulose-loaded sulfonated metal phthalocyanine, chitin-loaded sulfonated metal phthalocyanine, chitosan-loaded artemisinin or cellulose-loaded artemisinin, has good polishing efficiency and polishing effect on silicon carbide substrates, and significantly improves surface roughness.

[0135] It can be seen from Table 2 that in the polishing compositions of Examples 1 to 5, when the average particle size of the aluminum oxide abrasive is 100-1000 nm, the polishing rate of the silicon carbide substrate increases with the increase of the particle size; but when the average particle size is 100-300 nm, the surface roughness after polishing is significantly reduced.

[0136] As can be seen from Table 2, among the polishing compositions of Examples 8 to 16, the polishing compositions comprising chitosan-loaded sulfonated metal phthalocyanine, cellulose-loaded sulfonated metal phthalocyanine or chitin-loaded sulfonated metal phthalocyanine have better comprehensive polishing effects on silicon carbide substrates than the polishing compositions comprising chitosan-loaded artemisinin or cellulose-loaded artemisinin.

[0137] As can be seen from Table 2, among the polishing compositions of Examples 8 to 16, the polishing compositions comprising chitosan-loaded sulfonated copper phthalocyanine, cellulose-loaded sulfonated copper phthalocyanine, chitin-loaded sulfonated copper phthalocyanine or chitosan-loaded sulfonated cobalt phthalocyanine can maintain a good polishing rate for silicon carbide substrates and have a small surface roughness.

[0138] As can be seen from Table 2, in the polishing compositions of Examples 2 and 17 to 19, when the mass ratio of chitosan to sulfonated copper phthalocyanine is 0.2:1-0.5:1, the comprehensive polishing effect on the silicon carbide substrate is better than the polishing composition with a mass ratio of chitosan to sulfonated copper phthalocyanine of 0.7:1.

[0139] In addition, after the silicon carbide substrate was polished using the polishing compositions of Examples 1 to 20, the total thickness variation TTV of the substrate was ≤ 5 μm.

[0140] Although the present invention has been described in detail above by means of general description, specific implementation methods and tests, it is obvious to those skilled in the art that some modifications or improvements may be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. An acidic alumina polishing composition for rough polishing of a silicon carbide substrate, characterized in that: The composition comprises aluminum oxide abrasive, a dispersant, a suspending agent, a pH adjuster and water; Wherein, the suspending agent is selected from at least one of chitosan-loaded sulfonated metal phthalocyanine, cellulose-loaded sulfonated metal phthalocyanine, chitin-loaded sulfonated metal phthalocyanine, chitosan-loaded artemisinin or cellulose-loaded artemisinin, and the mass ratio of the chitosan, cellulose or chitin to the sulfonated metal phthalocyanine or artemisinin is 0.2:1-0.7:1; The pH value of the polishing composition is 2-6.

2. A polishing composition according to claim 1, characterized in that Calculated by mass percentage, the composition comprises 5-15% of aluminum oxide abrasive, 1-5% of dispersant, 1-5% of suspending agent, 1-5% of pH regulator, and the balance is water.

3. A polishing composition according to claim 1 or 2, characterized in that The particle size of the aluminum oxide abrasive is 100-1000 nm, preferably 100-300 nm.

4. A polishing composition according to claim 1 or 2, characterized in that The sulfonated metal phthalocyanine is selected from sulfonated copper phthalocyanine, sulfonated zinc phthalocyanine or sulfonated cobalt phthalocyanine.

5. A polishing composition according to claim 1 or 2, characterized in that: The suspending agent is selected from at least one of chitosan-supported sulfonated metal phthalocyanine, cellulose-supported sulfonated metal phthalocyanine, and chitin-supported sulfonated metal phthalocyanine.

6. A polishing composition according to claim 4, characterized in that The suspending agent is selected from at least one of chitosan-supported sulfonated copper phthalocyanine, cellulose-supported sulfonated copper phthalocyanine, chitin-supported sulfonated copper phthalocyanine, and chitosan-supported sulfonated cobalt phthalocyanine.

7. A polishing composition according to claim 1 or 2, characterized in that: The mass ratio of the chitosan, cellulose or chitin to the sulfonated metal phthalocyanine or artemisinin is preferably 0.2:1-0.5:

1.

8. A polishing composition according to claim 1 or 2, characterized in that: The dispersant is selected from at least one of polyethylene glycol, polypropylene glycol, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate or sodium dodecyl sulfate; the pH adjuster is selected from at least one of citric acid, formic acid, acetic acid, nitric acid, aluminum nitrate, sulfuric acid or glycine, and the pH adjuster is preferably aluminum nitrate.

9. A substrate polishing method, characterized in that: The substrate polishing method comprises: Mechanochemical polishing is performed using the polishing composition according to any one of claims 1 to 8, wherein the mechanochemical polishing is assisted by ultraviolet light irradiation.

10. A substrate polishing method as claimed in claim 9, characterized in that: The wavelength of the ultraviolet light used in the mechanical chemical grinding is 250-420nm; the power of the ultraviolet light used in the mechanical chemical grinding is 10-100mW.

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