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

Abstract

The invention discloses a silicon carbide substrate fine polishing composition and a preparation method and application thereof, and belongs to the technical field of semiconductor processing. The fine polishing composition for the silicon carbide substrate is a polishing composition obtained by adjusting the pH value of a basic system to 6.5-7 by using a pH regulator, the basic system is prepared from the following components in percentage by mass: 1%-40% of an abrasive material, 0.3%-5% of H2O2, 0.01%-10% of a catalyst, 0.1%-0.5% of a dispersing agent and 0.01%-1% of a complexing agent besides water; the catalyst comprises one or more of molybdate, tungstate and vanadate. According to the method, hydrogen peroxide is catalyzed by tungstate, molybdate or vanadate in a variable valence manner to generate active oxygen, a peroxide intermediate is formed, surface catalytic activation is performed, and the oxidation capacity of hydrogen peroxide is remarkably improved. The mechanism realizes the balance between high material removal rate and sub-nano surface quality in silicon carbide polishing, and is an efficient solution for replacing a traditional permanganate system.

Description

Technical Field

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

[0002] Silicon carbide (SiC), as one of the main representatives of third-generation semiconductors, is an ideal semiconductor material for manufacturing high-temperature, high-frequency, and high-power power electronic devices. Compared with traditional silicon-based products, devices made from SiC can provide core support for the upgrading of power electronic products, such as new energy vehicles, charging piles, and photovoltaic power generation. With the rapid development of the semiconductor industry, the size of electronic devices is shrinking, requiring wafer surface flatness to reach the nanometer level. Traditional planarization techniques can only achieve local planarization, while chemical mechanical polishing (CMP) can not only achieve global planarization, but also outperforms traditional planarization techniques in terms of processing performance and speed. For CMP of silicon carbide wafers, polishing slurry is a very important consumable. Chinese patent CN117586700A discloses a molybdate-containing silicon carbide wafer polishing slurry, its preparation method, and its application. The pH value of the molybdate-containing silicon carbide wafer polishing slurry is 9-12. It has the characteristics of strong cutting force, good surface quality, long cycle life, simple process operation, and low cross-contamination. However, if the pH value used is too high, it can easily cause environmental pollution. Chinese patent CN119019937A discloses a silicon carbide polishing solution. This solution fully utilizes the high polishing efficiency of both the catalyst and hydrogen peroxide, exhibiting higher oxidizing properties compared to polishing solutions containing only hydrogen peroxide. However, its applicability to 2-inch SiC wafers is limited. Chinese patent CN111518478A discloses a silicon carbide polishing solution and its application. This invention provides a silicon carbide polishing solution that uses a non-aqueous solvent instead of water, avoiding the limitation of the reaction activation energy, coordination properties, and redox potential of the components in the polishing solution by the aqueous solution. The silicon carbide polishing solution provided by this invention has good diamond suspension properties, improving polishing efficiency, and has no volatility issues, making it easy to store for long periods. However, the high price of diamond abrasives makes it unsuitable for industrial use.

[0003] In the field of silicon carbide wafer processing, due to the extremely high intrinsic hardness of the material, traditional polishing systems generally face bottlenecks such as low processing efficiency, rising production costs, and frequent surface scratches. Currently, mainstream polishing slurries mostly employ a combination of permanganate oxidants (such as KMnO4 / NaMnO4) and alumina abrasives. Their mechanism relies on strong oxidizing properties to break the C-Si bonds on the silicon carbide surface to improve material removal efficiency. However, this system has a significant drawback: excessive oxidation by permanganates easily leads to damage to the surface microstructure, resulting in decreased surface integrity. Although hydrogen peroxide (H2O2) is the preferred oxidant for fine polishing processes due to its mild oxidizing properties, its insufficient oxidizing power severely restricts material removal efficiency. Against this backdrop, enhancing the reactivity of the hydrogen peroxide system through catalytic activation strategies has become a key research direction for overcoming existing technological barriers. Summary of the Invention

[0004] In the field of silicon carbide wafer processing, due to the extremely high intrinsic hardness of the material, traditional polishing systems generally face bottlenecks such as low processing efficiency, rising production costs, and frequent surface scratches. Hydrogen peroxide remains the preferred oxidant for fine polishing of silicon carbide, but its oxidizing properties make it difficult to achieve high removal efficiency. In view of the shortcomings of existing technologies, this invention provides a silicon carbide substrate fine polishing composition, its preparation method, and its applications. By introducing a highly efficient catalytic system to activate the oxidation potential of hydrogen peroxide (H2O2), the bottleneck of insufficient oxidation capacity in traditional hydrogen peroxide systems is overcome. This polishing composition constructs a dynamic oxidation-mechanical synergistic removal mechanism through the synergistic effect of the catalyst and hydrogen peroxide: the catalyst not only enhances the selective dissociation of Si-C bonds on the silicon carbide surface by hydrogen peroxide, but also, combined with optimized nano-abrasives, forms precise control of "chemical softening-mechanical exfoliation." Compared to a single hydrogen peroxide system, its oxidation reaction rate is significantly improved, and it can effectively suppress surface over-etching and subsurface damage. Suitable for applications such as SiC-based power semiconductors and RF devices that have stringent requirements for atomic-level surface flatness and defect density, providing high-performance polishing solutions for third-generation semiconductor 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 silicon carbide substrate fine polishing composition, wherein the pH value of the base system is adjusted to 6.5-7 by a pH adjuster; the base system, in addition to water, comprises the following components by mass percentage: 1%-40% abrasive, 0.3%-5% H2O2, 0.01%-10% catalyst, 0.1%-0.5% dispersant and 0.01%-1% complexing agent; the catalyst comprises one or more of molybdate, tungstate and vanadate.

[0007] The transition metal ions such as tungsten (W), molybdenum (Mo), and vanadium (V) in the catalyst of this invention have multivalent state characteristics (e.g., W). 6+ / W 5+ Mo 6+ / Mo 5+ V 5+ / V 4+ In a hydrogen peroxide system, a reversible redox reaction can occur, and this cycle continuously generates reactive oxygen species whose oxidizing power far exceeds that of H2O2 itself, thus significantly enhancing the oxidizing activity of the system. Tungstates, molybdates, and other compounds can combine with H2O2 to form peroxyacid complexes. These intermediates possess even stronger oxidizing activity, and the resulting peroxyacid complexes release highly reactive oxygen species (such as O2) upon decomposition. - O2 and CO2 directly attack the Si-C bonds on the surface of silicon carbide, accelerating surface oxidation to generate easily removable SiO2 and CO2.

[0008] Preferably, the pH adjuster is sodium hydroxide, sodium carbonate, or sodium bicarbonate.

[0009] Preferably, the abrasive is silica sol.

[0010] More preferably, the silica sol has a silica mass concentration of 40%, wherein the silica particle size is 50-120 nm.

[0011] Preferably, the dispersant is sodium hexametaphosphate, sodium pyrophosphate, or aminotrimethylenephosphonic acid.

[0012] Preferably, the catalyst consists of at least two salts.

[0013] Preferably, the complexing agent is oxalate and / or citrate.

[0014] Catalysts composed of multiple salts exhibit stronger catalytic activity compared to catalysts composed of a single salt.

[0015] The second technical solution of the present invention provides a method for preparing the above-mentioned silicon carbide substrate fine polishing composition, comprising the following steps:

[0016] The abrasive, hydrogen peroxide, catalyst, dispersant, complexing agent and water are mixed evenly, and the pH value of the system is adjusted to 6.5-7 by adding a pH adjuster to obtain the silicon carbide substrate fine polishing composition.

[0017] In actual preparation, the hydrogen peroxide component is introduced in the form of hydrogen peroxide solution, and the amount of water used is reduced by the water content in the hydrogen peroxide solution accordingly.

[0018] The third technical solution of the present invention provides an application of the above-mentioned silicon carbide substrate fine polishing composition in the polishing of 3C-SiC, 4H-SiC, 6H-SiC or silicon carbide ceramic surfaces.

[0019] The beneficial technical effects of the present invention are as follows:

[0020] This invention significantly enhances the oxidation capacity of hydrogen peroxide by using tungstate, molybdate, or vanadate catalysis to generate active oxygen, form peroxide intermediates, and activate the surface catalysis. The addition of a complexing agent is not limited to preventing precipitation. It forms soluble complexes with catalyst metal ions (such as molybdenum and tungsten) with specific structures; these complexes themselves are more stable and efficient heterogeneous catalytic centers. This mechanism achieves a balance between high material removal rates and sub-nanometer surface quality in silicon carbide polishing, providing a highly efficient solution to replace traditional permanganate systems. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The hydrogen peroxide used in this embodiment of the invention is a 30% (w / w) aqueous solution of hydrogen peroxide.

[0027] Example 1

[0028] Preparation of a silicon carbide substrate fine polishing composition:

[0029] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 3% hydrogen peroxide, 1% sodium tungstate, and the remainder is deionized water.

[0030] A silicon carbide substrate fine polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium tungstate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0031] Example 2

[0032] Preparation of a silicon carbide substrate fine polishing composition:

[0033] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 3% hydrogen peroxide, 3% sodium tungstate, 0.5% sodium citrate, and the remainder is deionized water.

[0034] A silica sol with a mass concentration of 25% and a particle size of 100 nm was mixed with hydrogen peroxide with a mass concentration of 3%, sodium tungstate with a mass concentration of 3%, and the balance being deionized water.

[0035] A silicon carbide substrate fine polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium tungstate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0036] Example 3

[0037] Preparation of a silicon carbide substrate fine polishing composition:

[0038] Based on a total mass fraction of 100%, the following ingredients are prepared: 40% silica sol (containing 40wt% silica with a particle size of 100nm), 3% hydrogen peroxide, 3% sodium tungstate, 0.3% aminotrimethylenephosphonic acid, and the remainder is deionized water.

[0039] A silicon carbide substrate polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium tungstate, aminotrimethylene phosphonic acid and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0040] Example 4

[0041] Preparation of a silicon carbide substrate fine polishing composition:

[0042] Based on a total mass fraction of 100%, the following ingredients are prepared: 40% silica sol (containing 40wt% silica with a particle size of 120nm), 3% hydrogen peroxide, 3% sodium metavanadate, 0.5% sodium citrate, and the remainder is deionized water.

[0043] A silicon carbide substrate fine polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium metavanadate and deionized water and adjusting the pH value to 6 with sodium bicarbonate and sodium carbonate.

[0044] Example 5

[0045] Preparation of a silicon carbide substrate fine polishing composition:

[0046] Based on a total mass fraction of 100%, the following ingredients are prepared: 40% silica sol (containing 40wt% silica with a particle size of 120nm), 3% hydrogen peroxide, 6% sodium metavanadate, 0.5% sodium citrate, and the remainder is deionized water.

[0047] A silicon carbide substrate polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium metavanadate and deionized water and adjusting the pH value to 6.5 using sodium bicarbonate and sodium carbonate.

[0048] Example 6

[0049] Preparation of a silicon carbide substrate fine polishing composition:

[0050] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 120nm), 3% hydrogen peroxide, 8% sodium metavanadate, 0.5% sodium citrate, and the remainder is deionized water.

[0051] A silicon carbide substrate fine polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium metavanadate and deionized water and adjusting the pH value to 7 with sodium bicarbonate and sodium carbonate.

[0052] Example 7

[0053] Preparation of a silicon carbide substrate fine polishing composition:

[0054] Based on a total mass fraction of 100%, the following ingredients are prepared: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 15% hydrogen peroxide, 6% sodium metavanadate, 0.1% sodium hexametaphosphate, and the remainder is deionized water.

[0055] A silicon carbide substrate polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium metavanadate, sodium hexametaphosphate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0056] Example 8

[0057] Preparation of a silicon carbide substrate fine polishing composition:

[0058] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 15% hydrogen peroxide, 1% sodium molybdate, 0.5% sodium citrate, and the remainder is deionized water.

[0059] A silicon carbide substrate polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium molybdate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0060] Example 9

[0061] Preparation of a silicon carbide substrate fine polishing composition:

[0062] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 15% hydrogen peroxide, 3% sodium molybdate, 0.5% sodium citrate, and the remainder is deionized water.

[0063] A silicon carbide substrate polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium molybdate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0064] Example 10

[0065] Preparation of a silicon carbide substrate fine polishing composition:

[0066] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 15wt% silica with a particle size of 80nm and 25wt% silica with a particle size of 100nm), 15% hydrogen peroxide, 4% sodium metavanadate, 0.1% sodium hexametaphosphate, 0.5% sodium citrate, and the balance being deionized water.

[0067] A silicon carbide substrate fine polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium metavanadate, sodium hexametaphosphate and deionized water, and then adjusting the pH value to 6.5 with sodium bicarbonate and sodium carbonate.

[0068] Example 11

[0069] Preparation of a silicon carbide substrate fine polishing composition:

[0070] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 15% hydrogen peroxide, 3% sodium metavanadate, 0.5% sodium citrate, and the remainder is deionized water.

[0071] A silicon carbide substrate fine polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium metavanadate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0072] Example 12

[0073] Preparation of a silicon carbide substrate fine polishing composition:

[0074] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 15% hydrogen peroxide, 1.5% sodium molybdate, 1.5% sodium metavanadate, 0.5% sodium citrate, with the remainder being deionized water.

[0075] A silicon carbide substrate polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium molybdate, sodium metavanadate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0076] Example 13

[0077] Preparation of a silicon carbide substrate fine polishing composition:

[0078] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 15% hydrogen peroxide, 1.5% sodium molybdate, 1.5% sodium metavanadate, and the remainder is deionized water.

[0079] A silicon carbide substrate polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium molybdate, sodium metavanadate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0080] Example 14

[0081] Preparation of a silicon carbide substrate fine polishing composition:

[0082] Based on a total mass fraction of 100%, prepare: 25% silica sol (containing 40wt% silica with a particle size of 100nm), 15% hydrogen peroxide, 3% sodium metavanadate, and the remainder is deionized water.

[0083] A silicon carbide substrate fine polishing composition was obtained by mixing silica sol, hydrogen peroxide, sodium metavanadate and deionized water and adjusting the pH value to 10 with sodium hydroxide.

[0084] The performance of the silicon carbide substrate polishing compositions prepared in Examples 1-14 was tested.

[0085] Polishing experiment:

[0086] The polishing parameters are set as follows: Damping cloth is used as the polishing pad; the polishing pressure is 220 g / cm². 2 The upper plate rotated at 65 rpm, the lower plate at 60 rpm, and the polishing time was 4 hours. The polishing composition was recycled. After each polishing cycle, the polished wafers were ultrasonically cleaned in the cleaning solution for 10 minutes and then dried with nitrogen. The results are shown in Table 1.

[0087] Table 1

[0088]

[0089] As can be seen from Table 1, catalysts composed of multiple salts have stronger catalytic activity than catalysts composed of a single salt. The addition of complexing agents forms soluble catalytic centers, which makes the catalyst components more uniformly dispersed in the solution, ensuring that hydrogen peroxide can be decomposed efficiently and uniformly throughout the polishing process, thereby improving the polishing rate.

[0090] 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 silicon carbide substrate fine polishing composition, characterized in that, The pH of the base system is adjusted to 6.5-7 using a pH adjuster; the base system, in addition to water, comprises the following components by mass percentage: 1%-40% abrasive, 0.3%-5% H2O2, 0.01%-10% catalyst, 0.1%-0.5% dispersant, and 0.01%-1% complexing agent; the catalyst comprises one or more of molybdate, tungstate, and vanadate.

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

3. The silicon carbide substrate polishing composition according to claim 1, characterized in that, The abrasive is silica sol.

4. The silicon carbide substrate polishing composition according to claim 3, characterized in that, The silica sol has a silica mass concentration of 40%, and the silica particle size is 50-120 nm.

5. The silicon carbide substrate polishing composition according to claim 1, characterized in that, The dispersant is sodium hexametaphosphate, sodium pyrophosphate, or aminotrimethylenephosphonic acid.

6. The silicon carbide substrate polishing composition according to claim 1, characterized in that, The catalyst is composed of at least two salts.

7. The silicon carbide substrate polishing composition according to claim 1, characterized in that, The complexing agent is oxalate and / or citrate.

8. A method for preparing the silicon carbide substrate fine polishing composition according to any one of claims 1-7, characterized in that, Includes the following steps: The abrasive, hydrogen peroxide, catalyst, dispersant, complexing agent and water are mixed evenly, and the pH value of the system is adjusted to 6.5-7 by adding a pH adjuster to obtain the silicon carbide substrate fine polishing composition.

9. The use of the silicon carbide substrate polishing composition according to any one of claims 1-7 in the polishing of 3C-SiC, 4H-SiC, 6H-SiC or silicon carbide ceramic surfaces.

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