Polishing suspension and preparation method therefor, and polishing method for silicon carbide

Abstract

A polishing suspension and a preparation method therefor, and a polishing method for silicon carbide. The polishing suspension comprises the following components in parts by mass: 0.1-5 parts of an acrylic polymer; 0.1-10 parts of a special alcohol polyoxyethylene ether; 0.2-20 parts of a functional auxiliary; 65-105 parts of a solvent; and 0.1-1 part of a diamond abrasive. The acrylic polymer is a copolymer of a polymer A and an acrylic cross-linked polymer, wherein the polymer A is polyalkyl pentaerythritol or polyalkyl glycoside. The special alcohol polyoxyethylene ether comprises one or more of branched vicinal diol polyoxyethylene ether, acetylenic diol polyoxyethylene ether and branched secondary alcohol polyoxyethylene ether. The polishing suspension has a high suspending power, a high silicon carbide removal rate per unit time and low surface roughness, is not prone to causing pipeline blockage of polishing equipment, does not pollute polishing pads, has no influence on the performance of silicon carbide devices, and is not prone to scratching silicon carbide.

Description

Suspension polishing slurry and its preparation method and polishing method for silicon carbide Technical Field

[0001] This application relates to the field of polishing technology, and in particular to a suspension polishing slurry, its preparation method, and a polishing method for silicon carbide. Background Technology

[0002] Silicon carbide is a third-generation semiconductor material, characterized by its high temperature resistance, strong radiation resistance, high hardness, good wear resistance, and large bandgap. It is widely used in the semiconductor industry and high-precision optical devices. To meet market demands for ultra-smooth and ultra-clean surfaces, silicon carbide surfaces can be planarized through chemical or mechanical polishing.

[0003] Currently, there is relatively more research on the surface polishing of silicon carbide in the industry. However, due to the high surface hardness of silicon carbide, ordinary abrasives have poor self-sharpening properties when rubbing against it, resulting in a rapid decrease in material removal and poor process stability. Therefore, diamond, which has a higher hardness, is considered as an abrasive.

[0004] There are two main types of polishing slurries on the market for planarizing silicon carbide surfaces: dispersion systems and suspension systems. Although dispersion systems are simple to prepare, the abrasive particles tend to settle, resulting in uneven dispersion of the abrasive particles in the liquid film on the polishing pad during the polishing process. This can easily cause scratches on the wafer, thereby increasing the difficulty of subsequent processes. Therefore, suspension systems are more commonly found on the market.

[0005] The suspending agents in diamond abrasive-containing suspension polishing slurries are typically montmorillonite, bentonite, cellulose-based slurries, bio-adhesives, and polyurethane polymers. However, each of these suspension systems has its drawbacks. Montmorillonite and bentonite, as suspending agents, introduce excessive metal ions. Improper handling of these metal ions can lead to penetration into the silicon carbide, causing poor device performance. Furthermore, they tend to form short-stream rheological fluids, making the polishing equipment's piping difficult to clean and prone to blockage. Cellulose and bio-adhesive slurries, as suspending agents, generally have limited thickening capabilities, unstable viscosity, and are easily scratched on the silicon carbide surface. They are also difficult to control as long-stream rheological fluids. Polyurethane polymers, as suspending agents, tend to strongly adsorb and stain the polishing pad, resulting in poor product quality control. Additionally, all of these suspension systems suffer from issues such as easy stratification, low silicon carbide removal rate per unit time, and high surface roughness.

[0006] Therefore, it is of great significance to provide polishing fluids that have good suspension ability, high silicon carbide removal rate per unit time, low surface roughness, are not prone to clogging of polishing equipment pipelines, do not contaminate polishing pads, do not affect the performance of silicon carbide devices, and are not prone to scratching silicon carbide.

[0007] Summary of the Invention

[0008] Based on this, the first aspect of this application provides a suspension polishing fluid, the technical solution of which is as follows:

[0009] A suspension polishing liquid, comprising the following components in parts by weight:

[0010] The acrylic polymer is a copolymer of polymer A and an acrylic crosslinked polymer, wherein polymer A is polyalkyl pentaerythritol or polyalkyl glycoside;

[0011] The special alcohol polyoxyethylene ether includes one or more of branched vicinal diol polyoxyethylene ether, acetylsyl diol polyoxyethylene ether, and branched secondary alcohol polyoxyethylene ether.

[0012] The second aspect of this application provides a method for preparing the suspension polishing liquid as described above, the technical solution of which is as follows:

[0013] A method for preparing a suspension polishing slurry includes the following steps:

[0014] An acrylic polymer and a portion of a solvent are mixed to swell the acrylic polymer, resulting in a swollen solution.

[0015] The remaining solvent, a portion of the functional additives, the special alcohol polyoxyethylene ether, and the swelling solution are mixed to obtain the first intermediate solution;

[0016] The remaining functional additives and the intermediate liquid are mixed to obtain the second intermediate liquid;

[0017] The second intermediate liquid and diamond abrasive are mixed to prepare the suspension polishing liquid.

[0018] The third aspect of this application provides a method for polishing silicon carbide, the technical solution of which is as follows:

[0019] Silicon carbide was polished using the suspension polishing slurry described above.

[0020] Compared with traditional solutions, this application has the following advantages:

[0021] The suspended polishing slurry of this application contains diamond abrasive and uses a copolymer of polyalkyl pentaerythritol or polyalkyl glycoside and acrylic acid crosslinked polymer (acrylic polymer) as a suspending agent. In addition, a special alcohol polyoxyethylene ether is used. This suspension system can remain non-stratified for a long time and has good suspension stability. The main reason is that the acrylic polymer and the special alcohol polyoxyethylene ether form a dense, three-dimensional hydrogen-bonded entangled structure in the solvent, exhibiting a typical non-Newtonian fluid behavior. When no external force is applied, this structure prevents the diamond abrasive from settling, ensuring the abrasive's suspension and increasing product stability. Simultaneously, when the suspended polishing slurry of this application is subjected to external force, the polymer chains rapidly open, giving the suspension good fluidity. Furthermore, the special alcohol polyoxyethylene ether helps reduce surface tension. This allows the liquid film to spread and wet the polishing pad more quickly, increasing effective contact. In summary, the suspended polishing slurry of this application has a high material removal rate per unit time for polishing silicon carbide, low surface roughness, and high polishing efficiency. Simultaneously, the suspended polishing slurry has good fluidity, which can reduce the risk of scratches caused by the agglomeration of polishing debris over long periods, improving the scratch problem on the silicon carbide surface, ensuring product quality, and meeting the surface quality requirements of downstream device manufacturing. Furthermore, the special alcohol polyoxyethylene ether helps to transform the fluid from short-term rheological characteristics to long-term rheological characteristics, preventing debris accumulation and pipe blockage. Additionally, the suspended polishing slurry of this application is not easily adsorbed by the polishing pad and is easy to clean, which helps improve product yield. Finally, the suspended polishing slurry of this application can avoid introducing metal ions into the silicon carbide interior, thus preventing the silicon carbide device performance from being affected. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 is a schematic diagram of the preparation method of the suspension polishing slurry;

[0024] Figure 2 shows the scratches on the surface of the silicon carbide wafer under a microscope after polishing with the polishing solution in Example 1.

[0025] Figure 3 shows the scratches on the surface of the silicon carbide wafer under a microscope after polishing with the polishing solution in Example 2.

[0026] Figure 4 shows the scratches on the surface of the silicon carbide wafer under a microscope after polishing with the polishing solution of Comparative Example 2.

[0027] Figure 5 shows the scratches on the surface of the silicon carbide wafer under a microscope after polishing with the polishing solution of Comparative Example 5.

[0028] Figure 6 shows the scratches on the surface of the silicon carbide wafer under a microscope after polishing with the polishing solution of Comparative Example 6. Detailed Implementation

[0029] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0031] the term

[0032] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0033] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more or more.

[0034] In this application, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they can be selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.

[0035] In this application, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.

[0036] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0037] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0038] The first aspect of this application provides a suspension polishing liquid, which comprises the following components in parts by weight:

[0039] The acrylic polymer is a copolymer of polymer A and an acrylic crosslinked polymer, wherein polymer A is polyalkyl pentaerythritol or polyalkyl glycoside;

[0040] The special alcohol polyoxyethylene ether includes one or more of branched vicinal diol polyoxyethylene ether, acetylsyl diol polyoxyethylene ether, and branched secondary alcohol polyoxyethylene ether.

[0041] The suspended polishing slurry of this application contains diamond abrasive and uses a copolymer of polyalkyl pentaerythritol or polyalkyl glycoside and acrylic acid crosslinked polymer (acrylic polymer) as a suspending agent. In addition, a special alcohol polyoxyethylene ether is used. This suspension system can remain non-stratified for a long time and has good suspension stability. The main reason is that the acrylic polymer and the special alcohol polyoxyethylene ether form a dense, three-dimensional hydrogen-bonded entangled structure in the solvent, exhibiting a typical non-Newtonian fluid behavior. When no external force is applied, this structure prevents the diamond abrasive from settling, ensuring the abrasive's suspension and increasing product stability. Simultaneously, when the suspended polishing slurry of this application is subjected to external force, the polymer chains rapidly open, giving the suspension good fluidity. Furthermore, the special alcohol polyoxyethylene ether helps reduce surface tension. This allows the liquid film to spread and wet the polishing pad more quickly, increasing effective contact. In summary, the suspended polishing slurry of this application has a high material removal rate per unit time for polishing silicon carbide, low surface roughness, and high polishing efficiency. Simultaneously, the suspended polishing slurry has good fluidity, which can reduce the risk of scratches caused by the agglomeration of polishing debris over long periods, improving the scratch problem on the silicon carbide surface, ensuring product quality, and meeting the surface quality requirements of downstream device manufacturing. Furthermore, the special alcohol polyoxyethylene ether helps to transform the fluid from short-term rheological characteristics to long-term rheological characteristics, preventing debris accumulation and pipe blockage. Additionally, the suspended polishing slurry of this application is not easily adsorbed by the polishing pad and is easy to clean, which helps improve product yield. Finally, the suspended polishing slurry of this application can avoid introducing metal ions into the silicon carbide interior, thus preventing the silicon carbide device performance from being affected.

[0042] Optionally, the number-average molar mass of the acrylic polymer is 3 × 10⁻⁶. 6 g / mol~4×10 6 g / mol.

[0043] Optionally, the number-average molar mass of the branched o-diol polyoxyethylene ether is 300 g / mol to 1200 g / mol.

[0044] Optionally, the number-average molar mass of the acetylenic diol polyoxyethylene ether is 200 g / mol to 1800 g / mol.

[0045] Optionally, the number-average molar mass of the branched secondary alcohol polyoxyethylene ether is 500 g / mol to 2000 g / mol.

[0046] Preferably, the special alcohol polyoxyethylene ether is a branched o-diol polyoxyethylene ether.

[0047] Optionally, the particle size Dv50 of the diamond abrasive is 1μm to 4μm.

[0048] Optionally, the solvent includes polyols and water.

[0049] Optionally, the mass ratio of the polyol to water is (5-20):(60-85).

[0050] Optionally, the functional additives include dispersants, defoamers, and pH adjusters, wherein the mass ratio of the dispersant, defoamer, and pH adjuster is (0.1-5):(0.05-5):(0.1-10).

[0051] Optionally, the suspension polishing solution comprises the following components in parts by weight:

[0052] Optionally, the polyol is selected from one or more of isohexyl glycol, polyethylene glycol, propylene glycol, diethylene glycol, and triethylene glycol. Isohexyl glycol is preferred.

[0053] Optionally, the functional additives include one or more of dispersants, defoamers, and pH adjusters.

[0054] Optionally, the dispersant is selected from one or more of ammonium phosphate salt polymers, polyethyleneimine, polyacrylates, and ammonium polyacrylates. Preferably, it is an ammonium phosphate salt polymer.

[0055] Optionally, the defoamer is selected from one or more of ethylenediamine propylene oxide and ethylene oxide block polymers, silane-modified polyether polyols, polydimethylsiloxane, and alkoxy alcohols. Preferably, it is a silane-modified polyether polyol.

[0056] The weight-average molar mass of the ethylenediamine propylene oxide and ethylene oxide block polymer is 1 × 10⁻⁶. 4 g / mol~10×10 4 g / mol. The weight-average molar mass of silane-modified polyether polyol is 1 × 10⁻⁶ g / mol. 4 g / mol~10×10 4 g / mol. The number-average molar mass of polydimethylsiloxane is 1 × 10⁻⁶ g / mol. 4 g / mol~10×10 4 g / mol.

[0057] Optionally, the pH adjuster is selected from one or more of meglumine, ethylenediamine, triethylenetriaminepentaacetic acid, and monoethanolamine. Monoethanolamine is preferred.

[0058] Optionally, the suspension polishing liquid comprises the following components in parts by weight:

[0059] Optionally, the suspension polishing liquid comprises the following components in parts by weight:

[0060] Optionally, the suspension polishing liquid comprises the following components in parts by weight:

[0061] The suspension polishing slurry of this application has very good application prospects and potential for large-scale industrial promotion in the field of polishing silicon carbide and hard and brittle materials.

[0062] The second aspect of this application provides a method for preparing the suspension polishing liquid as described above, as shown in Figure 1, which includes the following steps:

[0063] S10. Mix an acrylic polymer with a portion of a solvent to swell the acrylic polymer, thus obtaining a swollen solution.

[0064] Optionally, a portion of the solvent refers to a portion of the water.

[0065] Optionally, the acrylic polymer and a portion of the solvent are mixed, including the following steps: the acrylic polymer is added to a portion of the solvent under stirring conditions of 600 r / min to 1000 r / min, and stirred for 20 min to 50 min until the mixture is uniform. After stirring, the mixture is allowed to swell fully for at least 2 hours before use.

[0066] S20. Mix the remaining solvent, functional additives, special alcohol polyoxyethylene ether, and the swelling solution to obtain an intermediate solution.

[0067] Optionally, the remaining solvent refers to the remaining water and polyol. The remaining solvent can be obtained by adding the polyol to the remaining water under stirring conditions of 200 r / min to 600 r / min and stirring for 10 min to 30 min until fully dissolved.

[0068] Optionally, mixing the remaining solvent, functional additives, special alcohol polyoxyethylene ether, and the swelling solution includes the following steps:

[0069] S21. Mix the remaining solvent, a portion of the functional additives, and a special alcohol polyoxyethylene ether to obtain the first intermediate liquid.

[0070] Optionally, some functional additives refer to defoamers, dispersants, and some pH adjusters.

[0071] Optionally, the remaining solvent, a portion of the functional additives, and the special alcohol polyoxyethylene ether are mixed, including the following steps: adding a portion of the functional additives and the special alcohol polyoxyethylene ether to the remaining solvent under stirring conditions of 200 r / min to 600 r / min, and stirring for 20 min to 50 min until fully dissolved.

[0072] S22. Mix the first intermediate liquid and the swelling liquid to obtain the second intermediate liquid.

[0073] Optionally, mixing the first intermediate liquid and the swelling solution includes the following steps: adding the swelling solution to the first intermediate liquid under stirring conditions of 200 r / min to 600 r / min, and stirring for 20 min to 50 min until the mixture is homogeneous. The swelling solution can be added slowly.

[0074] S23, a mixture of the second intermediate liquid and the remaining functional additives.

[0075] Optionally, the remaining functional additive is a remaining pH adjuster, used to adjust the system to a suitable pH value.

[0076] Optionally, the second intermediate liquid and the remaining functional additives are mixed, including the following steps: the remaining functional additives are added to the second intermediate liquid under stirring conditions of 200 r / min to 600 r / min, and the pH value is measured while adding. After reaching a suitable pH value, the mixture is stirred for 10 min to 30 min.

[0077] S30. Mix the intermediate liquid and diamond abrasive to prepare the suspension polishing liquid.

[0078] Optionally, mixing the intermediate liquid and the diamond abrasive includes the following steps: adding the diamond abrasive to the intermediate liquid under a stirring condition of 600 r / min to 1000 r / min, and stirring for 10 min to 30 min.

[0079] A third aspect of this application provides a method for polishing silicon carbide, comprising the following steps: polishing silicon carbide using a suspension polishing slurry as described above.

[0080] Alternatively, a polishing machine can be used for polishing. For example, the silicon carbide wafer to be polished can be adhered to a ceramic disk using solid or liquid wax, cooled to room temperature, and then placed in a polishing machine for polishing.

[0081] Optionally, the polishing process parameters include: rotation speed of 30 r / min to 80 r / min; pressure of 20 kg to 50 kg; time of 60 min to 90 min; and flow rate of 15 mL / min to 25 mL / min.

[0082] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0083] Acrylic polymers: copolymers of polyalkyl pentaerythritol and crosslinked acrylic acid polymers, with a number-average molar mass of 3.5 × 10⁻⁶. 6g / mol. Polyurethane: BASF PU1193. Branched vicinal glycol polyoxyethylene ether, number average molar mass 1200 g / mol. Acetylene glycol polyoxyethylene ether, number average molar mass 1800 g / mol. Branched secondary alcohol polyoxyethylene ether, number average molar mass 2000 g / mol. Ammonium phosphate ester polymer, Shanghai Zicheng International GS9181. Polyethyleneimine, GBK-PEI-2E3000. Polyacrylate, Klein PCE. Ammonium polyacrylate, Klein PL23. Silane-modified polyether polyol, weight average molar mass 23000 g / mol. Alkoxy alcohol, weight average molar mass 8000 g / mol. Ethylenediamine propylene oxide and ethylene oxide block polymer, weight average molar mass 30000 g / mol. Polydimethylsiloxane, number average molar mass 18000 g / mol. Polyethylene glycol, PEG400. The particle size Dv50 of the diamond abrasive is 2.5μm.

[0084] The suspension polishing slurry and its preparation method are as follows:

[0085] At 25°C, in a stirred tank, acrylic polymers were added to a portion of ultrapure water at a stirring speed of 900 r / min. The mixture was stirred for 30 min until homogeneous, then stirring was stopped and the mixture was allowed to stand for 2 h to swell, thus obtaining a swollen solution.

[0086] At 25°C and S20, in another stirred tank, with a stirring speed of 400 r / min, the polyol was first added to the remaining ultrapure water and stirred for 15 min until fully dissolved to obtain the remaining solvent. Then, under the same stirring conditions, the defoamer, dispersant, special alcohol polyoxyethylene ether, and part of the pH adjuster were added sequentially and stirred for 40 min to obtain the first intermediate liquid. Then, under the same stirring conditions, the swelling solution from the previous step was added and stirred for 40 min to obtain the second intermediate liquid. Finally, under the same stirring conditions, the remaining pH adjuster was added and stirred for 20 min to obtain the intermediate liquid.

[0087] S30. Add diamond abrasive to the intermediate liquid from the previous step with a stirring speed of 900 r / min and stir for 20 min to obtain a suspension polishing liquid.

[0088] Referring to the above-described method for preparing suspension polishing liquid, and referring to the components and parts by weight shown in Table 1, suspension polishing liquids of Examples 1 to 5 were prepared; referring to the components and parts by weight shown in Table 2, suspension polishing liquids of Examples 6 to 10 were prepared; and referring to the components and parts by weight shown in Table 3, suspension polishing liquids of Comparative Examples 1 to 6 were prepared.

[0089] Table 1. Components and weight parts of the suspension polishing liquid in Examples 1 to 5

[0090] Table 2. Components and weight parts of the suspension polishing liquid in Examples 6 to 10

[0091] Table 3. Components and weight parts of the suspension polishing solution of Comparative Examples 1 to 6

[0092] Analysis and testing methods:

[0093] The 6-inch silicon carbide wafers were polished using the suspension polishing slurries and polishing machines of Examples 1 to 10 and Comparative Examples 1 to 6, specifically as follows:

[0094] Step 1: Weigh the 6-inch silicon carbide wafer (accurate to 4 decimal places), then use liquid wax to attach it to a ceramic disc. After cooling to room temperature, place it in a polishing machine for polishing. The polishing conditions are: rotation speed 45 r / min; pressure 40 kg; time 70 min; flow rate 20 mL / min.

[0095] Step 2: After polishing, heat the silicon carbide wafer to remove it, clean the wax with isopropanol, rinse with pure water and sonicate twice, let it air dry, and weigh it (accurate to 4 decimal places).

[0096] Performance 1 Removal Rate Test

[0097] Calculate the removal rate using the following formula: Where Δm is the difference between the two weighings (g), and ρ is the density of silicon carbide (g / cm³). 3 ), where t is the polishing time (min) and S is the area of ​​the silicon carbide wafer.

[0098] Performance 2 Roughness Test

[0099] The roughness of the silicon carbide wafer was determined by taking the average value of three roughness tests at seven points on the front side of the polished wafer.

[0100] Performance 3 Scratch Test

[0101] The polished silicon carbide wafers were observed under a microscope at the same magnification. The depth and number of scratches were examined, and the degree of scratches was divided into 5 levels: scratch level 1 (almost no scratches), scratch level 2 (shallow and few scratches), scratch level 3 (shallow and many scratches), scratch level 4 (deep and few scratches), and scratch level 5 (deep and many scratches).

[0102] Performance 4 hover time test

[0103] The suspension polishing liquids of Examples 1 to 10 and Comparative Examples 1 to 6 were stored at room temperature in the dark, and the stratification after different storage times was examined to investigate their stability.

[0104] Performance 5 Cleaning ability test

[0105] After polishing, the ceramic disk is removed from the machine and the condition of the wafer edges on the ceramic disk, in addition to the polishing debris, is observed to examine its cleaning ability.

[0106] The test results for various performance parameters are shown in Tables 4 to 6. Figure 2 shows the scratches on the silicon carbide wafer surface under a microscope after polishing with the polishing solution of Example 1; Figure 3 shows the scratches on the silicon carbide wafer surface under a microscope after polishing with the polishing solution of Example 2; Figure 4 shows the scratches on the silicon carbide wafer surface under a microscope after polishing with the polishing solution of Comparative Example 2; Figure 5 shows the scratches on the silicon carbide wafer surface under a microscope after polishing with the polishing solution of Comparative Example 5; and Figure 5 shows the scratches on the silicon carbide wafer surface under a microscope after polishing with the polishing solution of Comparative Example 6; both show the scratches on the silicon carbide wafer surface under a microscope.

[0107] Table 4 shows the test results of various performance aspects in Examples 1 to 5.

[0108] Table 5 shows the test results of various performance aspects in Examples 6 to 10.

[0109] Table 6 shows the test results of various performance parameters for Comparative Examples 1 to 6.

[0110] Comparing the polishing data of the 6-inch silicon carbide wafers above, it is evident that the suspension polishing fluids of Examples 1 to 10 are typical thixotropic fluids, exhibiting good suspension capacity under static conditions. They did not separate after 15 days, demonstrating good suspension stability. Compared to Example 2 and Comparative Examples 1 to 6, the suspension polishing fluid of Example 2 demonstrates superior suspension capacity. Simultaneously, it exhibits good fluidity at higher shear rates, resulting in a high material removal rate per unit time, low surface roughness, and high polishing efficiency. Compared to Example 2 and Comparative Examples 1 to 6, the suspension polishing fluid of Example 2 demonstrates superior polishing efficiency. Furthermore, the good fluidity of the suspension polishing fluids of Examples 1 to 10 at higher shear rates reduces the risk of scratches caused by prolonged grinding debris accumulation. Compared to Example 2 and Comparative Examples 1 to 6, the suspension polishing fluid of Example 2 exhibits the lowest scratch severity. Moreover, compared to Comparative Example 3 using bentonite as a suspending agent, Example 2 uses an acrylic polymer as a suspending agent, which also avoids introducing metal ions into the silicon carbide, thus preventing any impact on the performance of the silicon carbide device. Meanwhile, compared to Comparative Example 4 which used polyurethane as a suspending agent, Example 2 used an acrylic polymer as a suspending agent, which does not produce strong adsorption and staining with the polishing pad, thus improving product yield. Furthermore, comparing Example 2 and Comparative Example 6, it is evident that branched 1,000-diol polyoxyethylene ether is beneficial for transforming the fluid from short-term to long-term rheological properties, preventing wear debris accumulation and clogging, and facilitating cleaning. Simultaneously, branched 1,000-diol polyoxyethylene ether also helps reduce surface tension, further improving polishing efficiency.

[0111] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0112] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A suspension polishing fluid, characterized in that, The components include the following parts by weight: The acrylic polymer is a copolymer of polymer A and an acrylic crosslinked polymer, wherein polymer A is polyalkyl pentaerythritol or polyalkyl glycoside; The special alcohol polyoxyethylene ether includes one or more of branched vicinal diol polyoxyethylene ether, acetylsyl diol polyoxyethylene ether, and branched secondary alcohol polyoxyethylene ether.

2. The suspension polishing fluid according to claim 1, characterized in that, The number-average molar mass of the acrylic polymer is 3 × 10⁻⁶. 6 g / mol~4×10 6 g / mol.

3. The suspension polishing fluid according to claim 1, characterized in that, Includes at least one of the following features: (1) The number-average molar mass of the branched o-diol polyoxyethylene ether is 300 g / mol to 1200 g / mol; (2) The number-average molar mass of the acetylacetonyl diol polyoxyethylene ether is 200 g / mol to 1800 g / mol; (3) The number-average molar mass of the branched secondary alcohol polyoxyethylene ether is 500 g / mol to 2000 g / mol.

4. The suspension polishing fluid according to any one of claims 1 to 3, characterized in that, The particle size Dv50 of the diamond abrasive is 1μm to 4μm.

5. The suspension polishing fluid according to any one of claims 1 to 3, characterized in that, The solvent includes polyols and water.

6. The suspension polishing fluid according to claim 5, characterized in that, Includes at least one of the following features: (1) The mass ratio of the polyol to water is (5-20):(60-85); (2) The polyol is selected from one or more of isohexyl glycol, polyethylene glycol, propylene glycol, diethylene glycol and triethylene glycol.

7. The suspension polishing fluid according to any one of claims 1 to 3 and 6, characterized in that, The functional additives include one or more of dispersants, defoamers, and pH adjusters.

8. The suspension polishing fluid according to claim 7, characterized in that, Includes at least one of the following features: (1) The functional additives include dispersants, defoamers and pH adjusters, and the mass ratio of the dispersants, defoamers and pH adjusters is (0.1-5):(0.05-5):(0.1-10); (2) The dispersant is selected from ammonium phosphate polymers, polyethyleneimine, polyacrylates, and ammonium polyacrylates. One or more; (3) The defoamer is selected from one or more of ethylenediamine propylene oxide and ethylene oxide block polymer, silane-modified polyether polyol, polydimethylsiloxane and alkoxy alcohol; (4) The pH adjuster is selected from one or more of meglumine, ethylenediamine, triethylenetriaminepentaacetic acid and monoethanolamine.

9. The suspension polishing fluid according to any one of claims 1 to 3, 6, and 8, characterized in that, The components include the following parts by weight:

10. A method for preparing a suspension polishing liquid according to any one of claims 1 to 9, characterized in that, Includes the following steps: An acrylic polymer and a portion of a solvent are mixed to swell the acrylic polymer, resulting in a swollen solution. The remaining solvent, functional additives, special alcohol polyoxyethylene ether, and the swelling solution are mixed to obtain an intermediate solution; The intermediate liquid and diamond abrasive are mixed to prepare the suspension polishing liquid.

11. A method for polishing silicon carbide, characterized in that, Includes the following steps: Silicon carbide is polished using the suspension polishing slurry according to any one of claims 1 to 9.

Images