Silicon carbide substrate rough polishing composition as well as preparation method and application thereof

Abstract

The invention discloses a silicon carbide substrate rough polishing composition and a preparation method and application thereof, and belongs to the technical field of semiconductor device processing. The rough polishing composition for the silicon carbide substrate is a polishing composition obtained by adjusting the pH value of a basic system to 3-4 by using a pH regulator; the basic system comprises the following components in percentage by mass: 2-10% of an abrasive, 2-6% of a first oxidant, 2-10% of a second oxidant and 0.5-2% of a dispersing agent besides water; the first oxidant is potassium permanganate; the second oxidizing agent is potassium persulfate or ferric persulfate. According to the method, the combination of potassium permanganate and persulfate is used as an oxidizing agent, and the rough polishing efficiency and uniformity of silicon carbide are remarkably improved through oxidation potential complementation, acidic environment synergy, free radical catalysis chain reaction and surface wettability optimization.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device processing technology, specifically relating to a coarse polishing composition for silicon carbide substrates, its preparation method, and its application. Background Technology

[0002] Silicon carbide (SiC) belongs to the third generation of semiconductor materials and has significant advantages in low-power, miniaturized, high-voltage, and high-frequency applications. Third-generation semiconductor materials, represented by SiC and gallium nitride (GaN), have a wider bandgap compared to the previous two generations, ensuring they can withstand higher electric field strengths and are suitable for fabricating high-voltage, high-frequency power devices. However, their processing is challenging, requiring efficient material removal and surface damage control during the rough polishing stage. Chemical mechanical polishing (CMP) is the mainstream process, but traditional polishing slurries have bottlenecks in terms of removal rate, surface quality, and stability. Patent CN112592663A discloses a processing technology for SiC substrates, using alumina micropowder as the abrasive and dispersants, suspending agents, defoamers, and lubricants as additives to formulate a polishing slurry, which is then used to process the SiC substrate surface. However, this method can only thin the SiC surface and cannot achieve the surface finish required by current SiC packaging processes. Patent CN118995056A discloses a silicon carbide polishing slurry containing two-dimensional materials. By introducing two-dimensional materials into the abrasive, the surface of SiC substrate is processed. However, its polishing rate is low. If the polishing rate is increased, the content of potassium permanganate needs to be increased, which can easily cause environmental pollution.

[0003] Currently, traditional coarse polishing solutions for silicon carbide substrates mainly consist of strong oxidants (potassium permanganate) and hard abrasives (alumina, zirconium oxide, cerium oxide, etc.). However, potassium permanganate consumes H₂ during the polishing process. + This leads to an increase in the pH of the solution system, affecting the dispersion stability of the polishing slurry system, causing abrasive grain agglomeration, and thus affecting the polishing rate. Furthermore, using superhard materials such as alumina or zirconium oxide as abrasives can result in surface scratches and excessive roughness. Summary of the Invention

[0004] To address the shortcomings of current silicon carbide substrate rough polishing solutions, such as low polishing rate, severe surface scratches, and poor dispersion, this invention provides a silicon carbide substrate rough polishing composition, its preparation method, and its applications. The provided silicon carbide substrate rough polishing composition not only solves the problems of poor stability and environmental pollution associated with oxidant-containing silicon carbide polishing compositions, but also features high cutting rate, stable surface quality, long cycle life, and ease of long-term storage, making it an ideal polishing composition material for semiconductor compound wafer manufacturing.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions of the present invention is to provide a coarse polishing composition for silicon carbide substrates, wherein the pH value of the base system is adjusted to 3-4 by a pH adjuster; the base system, in addition to water, comprises the following components by mass percentage: 2%-10% abrasive, 2%-6% first oxidant, 2%-10% second oxidant and 0.5%-2% dispersant; the first oxidant is potassium permanganate (KMnO4); the second oxidant is potassium persulfate (K2S2O8) or ferric persulfate (Fe2(SO5)3).

[0007] This invention utilizes a combination of potassium permanganate and persulfate as an oxidant. The standard oxidation potential of potassium permanganate is complementary to the sulfate and hydroxyl radicals generated by the decomposition of potassium persulfate or ferric persulfate. The free radicals generated by the decomposition of potassium persulfate or ferric persulfate have stronger oxidizing power, which can compensate for the oxidation limitations of potassium permanganate under specific conditions, thereby more efficiently oxidizing impurities on the silicon carbide surface or forming soluble products. Furthermore, the manganese dioxide (MnO2) generated by the reduction of potassium permanganate in the reaction can act as a catalyst to accelerate the decomposition of potassium persulfate to generate active free radicals (such as SO42-). - •), forming a chain reaction that further oxidizes organic matter or metallic impurities on the surface of silicon carbide.

[0008] Preferably, the pH adjuster is sodium hydroxide (NaOH) or aluminum nitrate (Al(NO3)3).

[0009] Preferably, the particle size of the abrasive is 200-300 nm.

[0010] Preferably, the abrasive is aluminum oxide (Al2O3) and / or cerium oxide (CeO2).

[0011] Preferably, the dispersant is sodium polyacrylate (PAA-Na).

[0012] This invention selects sodium polyacrylate as a dispersant, which can not only disperse abrasives, but also improve the stability of the system and make it easy to store for a long time.

[0013] The second technical solution of the present invention provides a method for preparing the above-mentioned silicon carbide substrate rough polishing composition, comprising the following steps:

[0014] Mix the abrasive, first oxidant, second oxidant, dispersant and water evenly, then add a pH adjuster to adjust the pH of the system to 3-4, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0015] Preferably, the order of addition of each component is as follows: the first oxidant is added to water and ultrasonically stirred at a stirring speed of 400-800 rpm for 0.5-1 h; then the second oxidant is added and stirring is continued for 0.5-1 h; the abrasive and dispersant are added to the solution in sequence and stirred for 2-4 h; finally, the pH adjuster is added and the pH of the system is adjusted to 3-4 to obtain the coarse polishing composition for silicon carbide substrate.

[0016] The third technical solution of the present invention provides an application of the above-mentioned silicon carbide substrate rough polishing composition in the polishing of silicon carbide substrate surface.

[0017] The beneficial technical effects of the present invention are as follows:

[0018] This invention uses a combination of potassium permanganate and persulfate as oxidants. Through complementary oxidation potentials, synergistic acidic environment, free radical catalytic chain reaction, and optimized surface wettability, it significantly improves the efficiency and uniformity of silicon carbide rough polishing. This synergistic effect is particularly important in chemical mechanical polishing (CMP), as it can efficiently remove surface impurities while reducing process defects caused by the limitations of a single oxidant.

[0019] The silicon carbide substrate rough polishing composition provided by this invention not only solves the problems of poor stability and environmental pollution of silicon carbide polishing compositions containing oxidants (by adding a small amount of strong oxidant to reduce environmental pollution), but also has the characteristics of high cutting rate, stable surface quality, long cycle life and easy long-term storage, making it an ideal polishing composition material for semiconductor compound wafer manufacturing. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0021] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0022] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] The pH adjuster used in this embodiment of the invention is sodium hydroxide or aluminum nitrate. When it is necessary to increase the pH value, alkaline sodium hydroxide is added, and when it is necessary to decrease the pH value, acidic aluminum nitrate is added.

[0026] The alumina used in this embodiment of the invention has a particle size of 200 nm.

[0027] Example 1

[0028] Preparation of a coarse polishing composition for silicon carbide substrates:

[0029] Based on a total mass fraction of 100%, prepare: 6% potassium permanganate; 6% potassium persulfate; 8% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0030] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 0.5 hours. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 9, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0031] Example 2

[0032] Preparation of a coarse polishing composition for silicon carbide substrates:

[0033] Based on a total mass fraction of 100%, prepare: 6% potassium permanganate; 3% potassium persulfate; 8% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0034] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 0.5 hours. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 9, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0035] Example 3

[0036] Preparation of a coarse polishing composition for silicon carbide substrates:

[0037] Based on a total mass fraction of 100%, prepare: 4% potassium permanganate; 4% potassium persulfate; 5% alumina; 0.5% sodium polyacrylate, with the remainder being deionized water.

[0038] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 0.5 hours. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 7, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0039] Example 4

[0040] Preparation of a coarse polishing composition for silicon carbide substrates:

[0041] Based on a total mass fraction of 100%, prepare: 3% potassium permanganate; 6% potassium persulfate; 6% alumina; 1.5% sodium polyacrylate, with the remainder being deionized water.

[0042] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 0.5 hours. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 3, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0043] Example 5

[0044] Preparation of a coarse polishing composition for silicon carbide substrates:

[0045] Based on a total mass fraction of 100%, prepare: 3% potassium permanganate; 3% potassium persulfate; 4% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0046] Potassium permanganate was added to deionized water and ultrasonically stirred at 600 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 0.5 hours. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 6, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0047] Example 6

[0048] Preparation of a coarse polishing composition for silicon carbide substrates:

[0049] Based on a total mass fraction of 100%, prepare: 3% potassium permanganate; 4.5% potassium persulfate; 3% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0050] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 0.5 hours. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 3.5, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0051] Example 7

[0052] Preparation of a coarse polishing composition for silicon carbide substrates:

[0053] Based on a total mass fraction of 100%, prepare: 3% potassium permanganate; 3% potassium persulfate; 4% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0054] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 0.5 hours. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 3, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0055] Example 8

[0056] Preparation of a coarse polishing composition for silicon carbide substrates:

[0057] Based on a total mass fraction of 100%, prepare: 3% potassium permanganate; 6% potassium persulfate; 6% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0058] Potassium permanganate was added to deionized water and ultrasonically stirred at 700 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 1 hour. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 9, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0059] Example 9

[0060] Preparation of a coarse polishing composition for silicon carbide substrates:

[0061] Prepare the following ingredients by total mass fraction: 3% potassium permanganate; 1.5% potassium persulfate; 4% alumina; 1% sodium polyacrylate; with the remainder being deionized water.

[0062] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 1 hour. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 9.5, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0063] Example 10

[0064] Preparation of a coarse polishing composition for silicon carbide substrates:

[0065] Prepare the following ingredients by total mass fraction: 3% potassium permanganate; 3% potassium persulfate; 3.5% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0066] Potassium permanganate was added to deionized water and ultrasonically stirred at 700 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 1 hour. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 9, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0067] Example 11

[0068] Preparation of a coarse polishing composition for silicon carbide substrates:

[0069] Based on a total mass fraction of 100%, prepare: 6% potassium permanganate; 4% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0070] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 1 hour. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 3, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0071] Example 12

[0072] Preparation of a coarse polishing composition for silicon carbide substrates:

[0073] Based on a total mass fraction of 100%, prepare: 6% potassium persulfate; 4% alumina; 1% sodium polyacrylate, with the remainder being deionized water.

[0074] Potassium permanganate was added to deionized water and ultrasonically stirred at 800 rpm for 1 hour. Then potassium persulfate was added and stirring was continued for 1 hour. Alumina and sodium polyacrylate were added to the solution in sequence and stirred for another 4 hours. Finally, a pH adjuster was added to adjust the pH of the system to 3, thus obtaining the coarse polishing composition for silicon carbide substrate.

[0075] The performance of the silicon carbide substrate rough polishing compositions prepared in Examples 1-12 was tested:

[0076] Polishing experiment:

[0077] The polishing parameters are set as follows: SUBA800 polishing pad; polishing pressure is 200g / cm. 2The upper plate rotated at 30 rpm, and the lower plate rotated at 20 rpm. The polishing composition was recycled, and the polishing time was 3 minutes. After each polishing cycle, the polishing pad was repaired with a 4-inch diamond repair disc for 5 minutes. The polished pad was then ultrasonically cleaned in cleaning solution for 10 minutes and dried with nitrogen. The results are shown in Table 1.

[0078] Table 1

[0079]

[0080] As shown in Table 1, stronger acidic conditions can effectively improve polishing efficiency, while increasing the mass of the abrasive may cause agglomeration, thus affecting the surface quality of the polished workpiece. In the coarse polishing solution system for silicon carbide wafers, the combination of potassium permanganate and potassium persulfate as oxidants exhibits a significant synergistic enhancement effect on the two key performance indicators of polishing rate and surface roughness compared to using potassium permanganate or potassium persulfate alone. As a strong oxidant, potassium permanganate can rapidly generate an easily removable soft silica oxide layer on the silicon carbide surface, with a fast reaction rate, mainly responsible for the initial rapid oxidation. Potassium persulfate decomposes in solution to produce peroxy radicals and sulfate radicals, which have strong oxidizing properties. These radicals have high oxidation potentials, can continuously oxidize the silicon carbide matrix, and can also effectively decompose and remove the byproducts generated after the potassium permanganate reaction, preventing the formation of a passivation layer on the surface and ensuring the continuous and efficient progress of the oxidation reaction.

[0081] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A coarse polishing composition for a silicon carbide substrate, characterized in that, Adjust the pH of the base system to 3-4 using a pH adjuster; In terms of mass percentage, the basic system, excluding water, also includes: 2%-10% abrasive, 2%-6% first oxidant, 2%-10% second oxidant, and 0.5%-2% dispersant; the first oxidant is potassium permanganate; the second oxidant is potassium persulfate or ferric persulfate.

2. The silicon carbide substrate coarse polishing composition according to claim 1, characterized in that, The pH adjuster is sodium hydroxide or aluminum nitrate.

3. The silicon carbide substrate coarse polishing composition according to claim 1, characterized in that, The abrasive has a particle size of 200-300 nm.

4. The silicon carbide substrate rough polishing composition according to claim 1, characterized in that, The abrasive is aluminum oxide and / or cerium oxide.

5. The silicon carbide substrate coarse polishing composition according to claim 1, characterized in that, The dispersant is sodium polyacrylate.

6. A method for preparing the coarse polishing composition for a silicon carbide substrate according to any one of claims 1-5, characterized in that, Includes the following steps: Mix the abrasive, first oxidant, second oxidant, dispersant and water evenly, then add a pH adjuster to adjust the pH of the system to 3-4, thus obtaining the coarse polishing composition for silicon carbide substrate.

7. The method for preparing the silicon carbide substrate rough polishing composition according to claim 6, characterized in that, The order of adding each component is as follows: add the first oxidant to the water and ultrasonically stir at a stirring speed of 400-800 rpm for 0.5-1 h. Then add the second oxidant and continue stirring for 0.5-1 h. Add the abrasive and dispersant to the solution in sequence and stir for 2-4 h. Finally, add the pH adjuster to adjust the pH value of the system to 3-4 to obtain the coarse polishing composition for silicon carbide substrate.

8. The use of the silicon carbide substrate rough polishing composition according to any one of claims 1-5 in the polishing of silicon carbide substrate surfaces.

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