Polishing solution, preparation method thereof and grinding method of silicon carbide substrate

Abstract

The invention discloses a polishing solution, a preparation method thereof and a grinding method of a silicon carbide substrate, the polishing solution comprises a polishing base solution and a catalyst, the catalyst is M2Mn3O8, and M is one of Co, Zn, Cr, Cu and Ca. The polishing solution provided by the invention is high in polishing efficiency, and the surface quality of a polished substrate is relatively good.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a polishing liquid and a preparation method thereof, and a grinding method for a silicon carbide substrate. Background Art

[0002] In commercial microelectronic components, smooth, defect-free substrates are very important for obtaining high-quality epitaxial layers. At present, the silicon carbide polishing process commonly used at home and abroad is the chemical mechanical polishing (CMP) process. The CMP process is a combination of chemical etching and mechanical grinding. On the basis of good polishing machine performance and suitable polishing pads, the silicon carbide substrate can obtain an ultra-smooth and ultra-flat surface. In addition to the polishing machine and polishing pad, the CMP polishing liquid is an important factor that determines the surface quality of the polished wafer.

[0003] In the field of chemical mechanical polishing technology, commonly used polishing liquids mainly use oxidants such as potassium permanganate, but there are problems such as limited oxidation reaction rate of the polishing liquid, low polishing efficiency, and poor surface quality of the substrate after polishing. Summary of the invention

[0004] Based on this, the present invention provides a polishing liquid and a preparation method thereof, and a method for grinding a silicon carbide substrate. The polishing liquid provided by the present invention can improve the polishing efficiency and improve the surface quality of the substrate after polishing.

[0005] In a first aspect, the present invention provides a polishing liquid comprising a polishing base liquid and a catalyst, wherein the catalyst is M2Mn3O8, and M is one of Co, Zn, Cr, Cu and Ca.

[0006] In one embodiment, the catalyst is Ca2Mn3O8.

[0007] In one embodiment, based on the total weight of the polishing liquid, the content of the catalyst is 0.01-2.0 wt %.

[0008] In one embodiment, based on the total weight of the polishing liquid, the polishing base liquid includes 5 to 20 wt% of abrasive, 0.5 to 5 wt% of a strong oxidant, 0.01 to 5.0 wt% of a dispersant, 0.02 to 3.0 wt% of a surfactant, 0.01 to 2.0 wt% of a pH adjuster, 0.01 to 2.0 wt% of a pH stabilizer, and 1 to 15 wt% of hydrogen peroxide.

[0009] In one embodiment, the pH of the polishing liquid is 2.5-9.

[0010] In one embodiment, the mass ratio of hydrogen peroxide to catalyst is (2-30):1.

[0011] In one embodiment, the abrasive includes one or more of aluminum oxide, zinc oxide, silicon oxide, cerium oxide, manganese oxide, magnesium oxide, silicon carbide, boron carbide, and diamond.

[0012] In one embodiment, the strong oxidant includes one or more of permanganate, hypochlorite, and dichromate.

[0013] In one embodiment, the dispersant includes one or more of dodecyldimethylamine oxide, hexadecyltrimethylammonium bromide, sodium dodecylsulfonate, sodium tripolyphosphate, sodium hexametaphosphate, N,N-dimethylacetamide, polyethylene glycol, fatty acid polyethylene glycol ester, and the like.

[0014] In one embodiment, the surfactant includes one or more of hexadecyltrimethylammonium chloride, ethylhexyl alcohol, phosphoric acid mercaptan, and polyethylene glycol ether.

[0015] In one embodiment, the pH adjuster includes one or more of hydrochloric acid, nitric acid, sodium hydroxide, and the like.

[0016] In one embodiment, the pH stabilizer includes an aqueous phosphate solution, and the phosphate includes one or more of NaH2PO4, Na2HPO4, K2HPO4, etc.

[0017] The first aspect of the present invention provides a polishing liquid, comprising a polishing base liquid and a catalyst, wherein the catalyst is M2Mn3O8, and M is one of Co, Zn, Cr, Cu and Ca. The scheme of the present invention utilizes the Fenton-like reaction activity of the M2Mn3O8 composite material, the valence phase of the Mn-based oxide is variable, and there are a large number of active sites and oxygen vacancies on the surface, which has good oxidation ability, and the transition element M and Mn double site synergistic effect in the molecule further increases the decomposition rate of the oxidant, generates OH· free radicals with strong oxidizing properties, improves the polishing efficiency, reduces the surface roughness, and improves the surface quality of the substrate after polishing.

[0018] In a second aspect, the present invention provides a method for preparing a polishing liquid, specifically, mixing and stirring a polishing base liquid and a catalyst to obtain the polishing liquid.

[0019] In a third aspect, the present invention provides a method for grinding a silicon carbide substrate, using the polishing liquid of the present invention to remove the damaged layer on the surface of the silicon carbide substrate by chemical mechanical grinding under ultraviolet light. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the prior art description. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0021] Figure 1 This is a test image of the silicon carbide substrate under a microscope provided in Example 1 of the present invention.

[0022] Figure 2 This is a roughness test chart of the silicon carbide substrate provided by Example 1 of the present invention using an atomic force microscope.

[0023] Figure 3 This is a test image of the silicon carbide substrate provided in Comparative Example 1 of the present invention under a microscope.

[0024] Figure 4 This is a roughness test chart of the silicon carbide substrate provided in Comparative Example 1 of the present invention using an atomic force microscope. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0027] Some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0028] Polishing fluid plays a vital role in semiconductor device manufacturing. It can effectively remove tiny particles, unevenness and contaminants on the surface of semiconductor substrates, making the surface smooth and uniform, thereby improving the performance and stability of chips. Polishing fluid is a key consumable in chemical mechanical polishing technology. Its quality and performance directly affect the polishing effect and are crucial to improving the quality of wafer manufacturing. Therefore, choosing a suitable polishing fluid is of great significance to ensure the quality and performance of semiconductor devices.

[0029] In the current polishing liquid system, the oxidant in the polishing liquid has an important influence on the polishing efficiency. It forms an oxide layer by chemically reacting with the elements of the polishing material, reducing the hardness of the material on the polishing surface, thereby facilitating mechanical removal. Therefore, controlling the concentration of the oxidant in the polishing liquid to achieve the best match with the mechanical action is the key to achieving efficient polishing.

[0030] In the prior art, the Fenton reaction activity of iron salts or iron oxides is mostly used to enhance the polishing efficiency of silicon carbide. The traditional Fenton reaction is based on Fe 2+ Reacts with H2O2 to decompose and produce OH·, a strong oxidizing agent. The reaction rate depends on Fe 2+ and Fe 3+ Therefore, Fe 2+ It is an important factor in determining the polishing rate. 2+ and Fe 3+ When the circulation is blocked, the reaction is limited, the utilization rate of H2O2 is very low, and the polishing effect is weakened. In addition, the optimal pH range of the Fenton reaction is relatively narrow, 3-4. When the pH is too high, Fe(OH)3 precipitation will form, affecting further catalytic reactions. When the pH is too low, the polishing liquid is too acidic and will react with H2O2 to neutralize, reducing the speed of the Fenton reaction and ultimately leading to a decrease in polishing efficiency. Existing catalysis can only use Fe 2+ The catalyst is single, and the traditional Fenton technology has a narrow pH range and Fe 3+ / Fe 2+ The obstructed circulation and the generation of a large amount of iron mud after the reaction are defects that are not conducive to the preparation of ultra-smooth and damage-free surfaces of silicon carbide.

[0031] Based on this, the present invention provides a polishing liquid and a preparation method thereof, and a grinding method for a silicon carbide substrate. The polishing liquid provided by the present invention includes a polishing base liquid and a catalyst, wherein the catalyst is M2Mn3O8, and M is one of Co, Zn, Cr, Cu and Ca. The scheme of the present invention utilizes the Fenton-like reaction activity of the M2Mn3O8 composite material, the valence phase of the Mn-based oxide is variable, and there are a large number of active sites and oxygen vacancies on the surface, which has good oxidation ability, and the transition element M and Mn double site synergistic effect in the molecule further increases the decomposition rate of the oxidant, generates OH· free radicals with strong oxidizing properties, improves the polishing efficiency, and improves the surface quality of the substrate after polishing.

[0032] In one embodiment, the catalyst is Ca2Mn3O8. The dual-site synergistic effect of Ca and Mn further increases the decomposition rate of H2O2, generates OH· free radicals with strong oxidizing properties, rapidly oxidizes the C of SiC, and accelerates the removal rate of SiC. In addition, the introduction of Ca can improve the defects of manganese oxide that are easy to phase change and deactivate, stabilize the phase structure of the catalyst, and improve the catalytic activity and service life of the catalyst.

[0033] In one embodiment, the preparation method of Ca2Mn3O8 is specifically as follows: dissolving hydrated calcium nitrate and hydrated manganese nitrate in deionized water, adding an appropriate amount of amino acid, stirring evenly to completely dissolve them, adding an appropriate amount of dilute ammonia water to adjust the pH of the solution to alkaline, stirring to obtain a gel, and calcining at high temperature to obtain a Ca2Mn3O8 composite material; or dissolving CaCl2 and hydrated manganese nitrate in deionized water, adding ethanol and stirring evenly, and then adding KHCO3 solution and stirring at room temperature to obtain a white precipitate, and drying and annealing the precipitate to obtain a Ca2Mn3O8 composite material.

[0034] In one embodiment, the content of the catalyst is 0.01-2.0wt% based on the total weight of the polishing liquid. The content of the catalyst in the polishing liquid is set within the range of 0.01-2%, mainly based on the comprehensive consideration of its catalytic effect and polishing efficiency. An appropriate amount of catalyst can accelerate the chemical reaction during the polishing process and improve the polishing efficiency; at the same time, this content range can also ensure the stability of the polishing liquid, avoid problems such as agglomeration of catalyst particles and reduced polishing efficiency, thereby ensuring the smooth progress of the polishing process.

[0035] In one embodiment, based on the total weight of the polishing liquid, the polishing base liquid includes 1 to 15 wt% of hydrogen peroxide. Hydrogen peroxide has strong oxidizing properties and can effectively remove the oxide layer and dirt on the surface of the workpiece, thereby improving the cleanliness and glossiness of the surface. Secondly, it can also react with metal ions to form stable compounds, thereby preventing the metal surface from corrosion or oxidation during the polishing process. Adding 1 to 15 wt% of hydrogen peroxide can not only ensure sufficient oxidation effect, but also avoid excessive oxidation or safety hazards caused by too high concentration. Optionally, the content of hydrogen peroxide can be 1 wt%, 2 wt%, 3 wt%, 5 wt%, 7 wt%, 10 wt%, 15 wt%.

[0036] In one embodiment, the mass ratio of hydrogen peroxide to the catalyst is (2-30):1. Hydrogen peroxide is used as an oxidant in the polishing liquid, and its concentration and dosage directly affect the polishing effect and efficiency. The catalyst can accelerate the decomposition of hydrogen peroxide and improve its activity, thereby enhancing the polishing effect. Reasonable control of the mass ratio of hydrogen peroxide to the catalyst helps to achieve efficient and uniform polishing. Secondly, the setting of the ratio range (2-30):1 fully considers different polishing requirements and material properties. Under the condition of an appropriate amount of hydrogen peroxide, within a higher ratio range, such as 20:1 or 30:1, it is suitable for situations where the polishing requirements are not too strict or the material is more sensitive, so as to avoid excessive oxidation or damage. In a lower ratio range, such as 2:1 or 5:1, it is suitable for situations where higher polishing efficiency is required or where it is difficult to remove dirt. Within the scope of the present invention, the catalyst can give full play to its catalytic effect, improve the utilization rate of hydrogen peroxide, and reduce the polishing cost.

[0037] In one embodiment, the pH of the polishing liquid is 2.5 to 9. The pH value affects the formation of the surface film, the removal and decomposition of the material, and the viscosity of the polishing liquid. When the pH of the polishing liquid is within the range of 2.5 to 9, the polishing liquid can maintain its stability and effectiveness, and improve the polishing quality and surface gloss. Optionally, the pH value of the polishing liquid can be 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 7.0, 8.0 or 9.0.

[0038] In one embodiment, based on the total weight of the polishing liquid, the polishing base liquid includes 5 to 20 wt% of abrasives. The abrasive content within this range ensures that the silicon carbide polishing liquid can maintain a high cutting force during polishing, effectively remove oxides, impurities and tiny flaws on the surface of the material, and make the polishing process stable and controllable, preventing over-polishing or under-polishing. At the same time, an appropriate amount of abrasives can also improve the utilization rate of the polishing liquid, reduce waste, and reduce costs. In addition, the selection of this abrasive content range also fully considers the balance between polishing efficiency and polishing quality, so that the surface of the polished material can achieve an ideal finish and consistency. Optionally, the abrasive content can be 5wt%, 7wt%, 9wt%, 11wt%, 13wt%, 15wt%, 17wt%, 20wt%. Specifically, the abrasive includes one or more of aluminum oxide, zinc oxide, silicon oxide, cerium oxide, manganese oxide, magnesium oxide, silicon carbide, boron carbide, and diamond. These abrasives have high hardness, good wear resistance and chemical stability. During the polishing process, they can effectively remove oxides, impurities and uneven parts on the surface of the material, improve the polishing efficiency and quality, and are not easy to chemically react with the surface of the material during the polishing process, thereby maintaining the purity and consistency of the polished surface. For example, aluminum oxide has high hardness and wear resistance, can effectively improve grinding efficiency and processing accuracy, and zinc oxide can enhance the thermal stability and accuracy of the abrasive.

[0039] In one embodiment, based on the total weight of the polishing liquid, the polishing base liquid includes 0.5 to 5 wt% of a strong oxidant. The strong oxidant exhibits good stability in the polishing liquid, can continuously exert an oxidizing effect, and maintain the durability of the polishing effect. At the same time, they are compatible with other polishing liquid components and can work synergistically to improve polishing efficiency and polishing quality. Optionally, the strong oxidant includes one or more of permanganate, hypochlorite, and dichromate. Permanganate, hypochlorite, and dichromate all have strong oxidizing properties. These substances are easy to obtain electrons in chemical reactions and can effectively remove oxide layers, dirt, and impurities on the metal surface to achieve cleaning and gloss enhancement effects. Optionally, the content of the strong oxidant can be 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0040] In one embodiment, the polishing base liquid includes 0.01 to 5.0 wt% of a dispersant based on the total weight of the polishing liquid. The presence of the dispersant significantly improves the dispersibility of the solid particles in the polishing liquid, ensuring the uniformity and consistency of the polishing process. By reducing the agglomeration and precipitation of the particles, the dispersant helps to improve the polishing efficiency, reduce the surface roughness, and thus achieve a high-quality polishing effect. The selection of the dispersant ratio range takes into account both the polishing effect and the cost-effectiveness. Optionally, the content of the dispersant can be 0.01 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 5 wt%. Specifically, the dispersant includes one or more of dodecyl dimethylamine oxide, hexadecyl trimethyl ammonium bromide, sodium dodecyl sulfonate, sodium tripolyphosphate, sodium hexametaphosphate, N, N-dimethylacetamide, polyethylene glycol, fatty acid polyethylene glycol esters, etc. These substances can effectively disperse the solid particles in the liquid, thereby improving the performance and effect of the polishing liquid. For example, dodecyl dimethylamine oxide is a substance with excellent surface activity, which can reduce the surface tension of the liquid and help to evenly disperse solid particles in the liquid; hexadecyl trimethyl ammonium bromide (also known as 1631 bromine-type surfactant) is a cationic surfactant with good penetration, dispersion and emulsification properties. It can effectively coordinate with anionic, nonionic and amphoteric surfactants to improve the dispersion effect of the polishing liquid.

[0041] In one embodiment, the polishing base liquid includes 0.01-5.0wt% of a surfactant based on the total weight of the polishing liquid. The surfactant can effectively reduce the surface tension of the polishing liquid, enhance the wettability and permeability of the liquid to solid particles, thereby significantly improving the dispersion effect and polishing efficiency during the polishing process. Adding 0.01-5.0wt% of a surfactant can promote the uniform distribution of particles in the polishing liquid, reduce agglomeration and precipitation, and thus achieve a high-quality polishing surface. Optionally, the content of the surfactant can be 0.02wt%, 0.1wt%, 0.2wt%, 0.5wt%, 1wt%, 2wt%, 3wt%. Specifically, the surfactant includes one or more of hexadecyltrimethylammonium chloride, ethylhexyl alcohol, phosphoric acid mercaptan, and polyethylene glycol ether. The above substances can reduce surface tension, enhance wettability and permeability, and adjust the properties of the particle surface, thereby optimizing the polishing process. Exemplarily, hexadecyltrimethylammonium chloride has good adsorption and dispersibility, can be adsorbed on the surface of polishing particles, and keeps a certain distance between particles through electrostatic action to prevent agglomeration, thereby improving the dispersibility and stability of the polishing liquid.

[0042] In one embodiment, the polishing base liquid includes 0.01-2.0wt% of a pH regulator based on the total weight of the polishing liquid. The pH regulator can adjust and control the pH of the polishing liquid, thereby optimizing the chemical reaction rate and particle dispersibility during the polishing process. Adding 0.01-2.0wt% of a pH regulator helps reduce the corrosion of the polishing liquid on the surface of the workpiece, while enhancing the polishing effect and improving the surface quality. Optionally, the content of the pH regulator can be 0.01wt%, 0.02wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.5wt%, 1wt%, 2wt%. Specifically, the pH regulator includes one or more of hydrochloric acid, nitric acid, sodium hydroxide, etc. These acid-base regulators have high practicality and economy in the manufacture of polishing liquids. At the same time, when they interact with other components in the polishing liquid, they can maintain stability and compatibility to ensure the smooth progress of the polishing process.

[0043] In one embodiment, the polishing base liquid includes 0.01 to 2.0 wt% of a pH stabilizer based on the total weight of the polishing liquid. The pH stabilizer can effectively buffer the acid-base changes in the polishing liquid. Adding 0.01 to 2.0 wt% of a pH stabilizer can promote the polishing liquid to maintain a stable pH value during long-term use, thereby maintaining the consistency and efficiency of the polishing effect. Optionally, the content of the pH stabilizer can be 0.01 wt%, 0.02 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, or 2 wt%. Specifically, the pH stabilizer includes an aqueous phosphate solution, and the phosphate includes one or more of NaH2PO4, Na2HPO4, K2HPO4, etc. These substances can absorb or release hydrogen ions (H2PO4) within a certain pH range. + ), thereby adjusting the pH of the solution. For example, when the solution is too acidic, these compounds can release hydroxide ions (OH - ), neutralizing excess hydrogen ions and raising the pH value of the solution; conversely, when the solution is too alkaline, they can absorb hydroxide ions and lower the pH value. In addition, these compounds also have a certain chelating ability and can combine with metal ions in the solution to reduce the impact of metal ions on the pH value. For example, they can chelate metal ions such as iron and copper to prevent these ions from catalyzing oxidation reactions, thereby further stabilizing the pH value of the solution.

[0044] In one embodiment, the polishing base liquid includes 60-90wt% deionized water based on the total weight of the polishing liquid, and the deionized water fully penetrates into the micropores and cracks on the surface to clean the surface and remove impurities and dirt, which helps to keep the polishing surface clean and smooth, thereby improving the polishing effect. Optionally, the content of deionized water can be 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%.

[0045] In a second aspect, the present invention provides a method for preparing a polishing liquid, wherein a polishing base liquid and a catalyst are mixed and stirred to obtain the polishing liquid. In a specific method for preparing a silicon carbide polishing liquid, deionized water, an oxidant, a dispersant, a surfactant, a pH regulator, and a pH stabilizer are first added to a container according to a weight ratio and stirred until clear, and then a polishing abrasive is added to the above solution stirred to clarify according to a weight ratio, and then an appropriate amount of a catalyst is added and stirred evenly to obtain a silicon carbide polishing liquid.

[0046] In a third aspect, the present invention provides a method for grinding a silicon carbide substrate. The polishing liquid of the present invention is prepared, and a portion of the silicon carbide substrate is removed by chemical mechanical grinding under the irradiation of ultraviolet light. By irradiating the Fenton reaction liquid with ultraviolet light, the decomposition of the H2O2 solution can be accelerated under the irradiation of ultraviolet light, and the additional hydroxyl radicals ·OH produced increase the hydroxyl radical ·OH concentration of the Fenton-like reaction system. On the other hand, the irradiation of ultraviolet light can enable the electrons in the silicon carbide to obtain energy, so that it reacts with ·OH to generate SiO2. During the polishing process, the hardness of the surface of the silicon carbide wafer can be reduced, and it is easier to remove when it is rubbed by the polishing pad and abrasive, which can effectively improve the polishing efficiency of the wafer and improve the surface quality. Therefore, the effective combination of the Fenton-like reaction catalyst and hydrogen peroxide under ultraviolet light irradiation can enhance the polishing efficiency of silicon carbide and improve the surface quality of silicon carbide.

[0047] The technical solution of the present invention is further illustrated below through specific embodiments and comparative examples.

[0048] Example 1

[0049] (1) Preparation of polishing liquid

[0050] The chemical mechanical polishing liquid is composed of a polishing base liquid and a catalyst, wherein the polishing base liquid is: 10% nano-alumina powder, 2% potassium permanganate, 15% hydrogen peroxide, 0.2% hexadecyltrimethylammonium chloride, 0.1% sodium dodecylsulfonate, and the balance is deionized water, with an appropriate amount of pH regulator added, and an appropriate amount of NaH2PO4 aqueous solution added as a pH stabilizer; the catalyst is Ca2Mn3O8, and the content of the catalyst is 0.5%.

[0051] The catalyst is placed in the polishing base liquid, and the mixture is fully mixed and homogenized to obtain the polishing liquid.

[0052] (2) Chemical mechanical polishing of 6-inch silicon carbide substrate

[0053] The method for polishing the surface of silicon carbide using the chemical mechanical polishing liquid comprises the following specific steps:

[0054] The silicon carbide substrate sheet was pressed from top to bottom onto a polishing disc with a polishing pad attached thereto. The pressure required during the polishing process was 300 kgf, the rotation speed of the polishing disc was 35 rpm, and the polishing time was 60 min.

[0055] The chemical mechanical polishing test was carried out on a chemical mechanical polishing test platform built with an ultraviolet light source having a wavelength of λ=300nm as the external environment.

[0056] Embodiments 2 to 17

[0057] The polishing liquid components in Examples 2 to 17 are shown in Table 1, and the remaining steps are consistent with Example 1.

[0058] Comparative Example 1

[0059] (1) Preparation of polishing liquid

[0060] The chemical mechanical polishing liquid is composed of a polishing base liquid and a catalyst, wherein the polishing base liquid is: 11% nano-alumina powder, 2% potassium permanganate, 15% hydrogen peroxide, 0.2% hexadecyltrimethylammonium chloride, 0.1% sodium dodecylsulfonate, and the balance is deionized water, with an appropriate amount of pH regulator added, and an appropriate amount of NaH2PO4 aqueous solution added as a pH stabilizer; the catalyst is Fe2SO4, and the content of the catalyst is 2%.

[0061] The catalyst is placed in the polishing base liquid, and the mixture is fully mixed and homogenized to obtain the polishing liquid.

[0062] (2) Chemical mechanical polishing of 6-inch silicon carbide substrate

[0063] The method for polishing the surface of silicon carbide using the chemical mechanical polishing liquid comprises the following specific steps:

[0064] The silicon carbide substrate sheet was pressed from top to bottom onto a polishing disc with a polishing pad attached thereto. The pressure required during the polishing process was 300 kgf, the rotation speed of the polishing disc was 35 rpm, and the polishing time was 60 min.

[0065] Comparative Examples 2 to 6

[0066] The polishing liquid components in Comparative Examples 2 to 6 are shown in Table 1, and the remaining steps are consistent with Comparative Example 1.

[0067] Table 1 Components of polishing liquid in Examples and Comparative Examples (wt%)

[0068]

[0069]

[0070] Test method:

[0071] (1) Polishing rate test

[0072] Polishing rate test method: Place the cleaned silicon carbide wafer on a FRT (MicroProf200) flatness tester to test its thickness. Removal rate = (thickness before polishing - thickness after polishing) / polishing time.

[0073] (2) Roughness test

[0074] The roughness of the cleaned silicon carbide wafer was tested using the NCM-Frequency Sweep test module in the AFM test equipment (ParkNX20).

[0075] (3) Polishing quality test

[0076] The surface quality of the silicon carbide wafer was observed using a microscope (VHX-7000) at a magnification of 50 times to check for surface defects such as scratches.

[0077] (4) Cycle life

[0078] The time from the start of polishing to the time when the polishing liquid can no longer polish the silicon carbide wafer is recorded as the cycle life.

[0079] Table 2 Test results of polished silicon carbide substrate

[0080]

[0081] From the results in Table 1 and Table 2, it can be seen that the removal rate of the silicon carbide substrate polished in Example 1 is 8.8 μm / h, and no scratches can be seen under a microscope ( Figure 1 ), roughness Ra<1.0nm, roughness test results see Figure 2 Comparative Example 1 The removal rate of the silicon carbide substrate polishing is 5.8 μm / h, and scratches can be seen under the microscope ( Figure 3 ), roughness Ra>1.0nm, roughness test results see Figure 4 . The Fenton-like reaction system adopted by the present invention can improve the removal rate while ensuring a small roughness, achieve a better surface roughness, reduce the amount of scratch defects, and remove the damaged layer. Furthermore, when the ratio of hydrogen peroxide to the catalyst is (2-30):1, the catalyst in the polishing liquid catalyzes hydrogen peroxide to generate a large amount of highly oxidizing ·OH through a Fenton-like reaction under the co-catalysis of ultraviolet irradiation, which oxidatively corrodes the damaged layer of silicon carbide, forming an easily removable SiO2 oxide layer on its surface, thereby accelerating the polishing rate.

[0082] The test results show that compared with the traditional Fenton catalytic system, the Fenton-like reaction system adopted in the present invention can improve the removal rate while ensuring the roughness, achieve better surface roughness, reduce the amount of scratch defects, and remove the damaged layer.

[0083] The above is a preferred embodiment of the present application, but it should not be understood as limiting the scope of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A polishing liquid, characterized in that: The invention comprises a polishing base liquid and a catalyst, wherein the catalyst is M2Mn3O8, and M is one of Co, Zn, Cr, Cu and Ca.

2. The polishing liquid according to claim 1, characterized in that The catalyst is Ca2Mn3O8.

3. The polishing liquid according to any one of claim 1, characterized in that Based on the total weight of the polishing liquid, the content of the catalyst is 0.01-2.0wt%.

4. The polishing liquid according to claim 1, characterized in that Based on the total weight of the polishing liquid, the polishing base liquid includes 5 to 20 wt% of abrasive, 0.5 to 5 wt% of a strong oxidant, 0.01 to 5.0 wt% of a dispersant, 0.02 to 3.0 wt% of a surfactant, 0.01 to 2.0 wt% of a pH regulator, 0.01 to 2.0 wt% of a pH stabilizer, and 1 to 15 wt% of hydrogen peroxide.

5. The polishing liquid according to any one of claims 1 to 4, characterized in that: The pH value of the polishing liquid is 2.5-9.

6. The polishing liquid according to any one of claims 1 to 4, characterized in that: The mass ratio of the hydrogen peroxide to the catalyst is (2-30):

1.

7. The polishing liquid according to any one of claims 1 to 4, characterized in that: The abrasive includes one or more of aluminum oxide, zinc oxide, silicon oxide, cerium oxide, manganese oxide, magnesium oxide, silicon carbide, boron carbide, and diamond.

8. The polishing liquid according to any one of claims 1 to 4, characterized in that: The strong oxidant includes one or more of permanganate, hypochlorite and dichromate.

9. The polishing liquid according to any one of claims 1 to 4, characterized in that: The dispersant includes one or more of dodecyldimethylamine oxide, hexadecyltrimethylammonium bromide, sodium dodecylsulfonate, sodium tripolyphosphate, sodium hexametaphosphate, N,N-dimethylacetamide, polyethylene glycol, fatty acid polyethylene glycol ester, and the like.

10. The polishing liquid according to any one of claims 1 to 4, characterized in that: The surfactant includes one or more of hexadecyltrimethylammonium chloride, ethylhexyl alcohol, phosphoric acid mercaptan, and polyethylene glycol ether.

11. The polishing liquid according to any one of claims 1 to 4, characterized in that: The pH adjuster includes one or more of hydrochloric acid, nitric acid, sodium hydroxide and the like.

12. The polishing liquid according to any one of claims 1 to 4, characterized in that: The pH stabilizer includes a phosphate aqueous solution, and the phosphate includes one or more of NaH2PO4, Na2HPO4, K2HPO4, etc.

13. The method for preparing the polishing liquid according to any one of claims 1 to 12, characterized in that: The polishing base liquid and the catalyst are mixed and stirred to obtain the polishing liquid.

14. A method for grinding a silicon carbide substrate, characterized in that: A portion of the silicon carbide substrate is removed by chemical mechanical polishing under ultraviolet light using the polishing liquid as described in any one of claims 1 to 12.

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