A silicon carbide polishing liquid containing a composite silica abrasive, and a preparation method and application thereof

Abstract

The application relates to the technical field of material processing, in particular to a silicon carbide polishing solution containing composite silica sol abrasives and a preparation method and application thereof. The silicon carbide polishing solution containing composite silica sol abrasives comprises the following components in percentage by mass: composite silica sol abrasives 1-20%, dispersing agent 0.01-1%, oxidant 0.1-10%, auxiliary oxidant 1-20%, pH regulator 0.001-0.1%, and the rest is deionized water; the composite silica sol abrasives comprise at least two kinds of silica sols with a particle size difference of more than 50 nm. The application adopts silica sols with different particle sizes to prepare irregular composite abrasives, cooperates with various auxiliary agents to improve the double effects of chemical oxidation and mechanical friction, can enhance the mechanical friction points and wear resistance of the silicon carbide polishing solution, and can not easily cause scratches and damage layers on the wafer surface in the polishing process, and the surface roughness is low.

Description

Technical Field

[0001] This invention relates to the field of materials processing technology, and in particular to a silicon carbide polishing slurry containing composite silica sol abrasive, its preparation method, and its application. Background Technology

[0002] With the rapid growth in demand for high-frequency, high-power radio frequency and power electronics in fields such as 5G and new energy, third-generation semiconductor materials, led by silicon carbide, are gradually entering large-scale application and industrialization. The processing quality and precision of silicon carbide substrates directly affect the performance of devices. Chemical mechanical polishing (CMP) is considered one of the most effective methods to achieve global planarization and ultra-smooth surfaces. Polishing slurries typically use high-hardness abrasives such as diamond micron powder and alumina particles. While strong mechanical action can increase the polishing speed, it easily forms microcracks, scratches, and subsurface damage layers, resulting in low yield of finished products. In existing technologies, alumina and cerium oxide-based polishing slurries generally suffer from numerous wafer surface defects after polishing, failure to meet roughness requirements, and low wafer yield, making it difficult to achieve the optimal dynamic balance between chemical reaction and mechanical friction. When the mechanical action of the polishing slurry abrasive is too strong, it can easily cause surface scratches, subsurface damage, and excessive roughness. On the other hand, excessive chemical action can lead to an excessively fast oxidation rate on the wafer surface. The residual softening layer cannot be polished away in time, and defects such as "orange peel" and pits appear on the substrate surface, which are difficult to repair.

[0003] Existing fine polishing solutions using silica sol as an abrasive have problems such as low polishing rate, long processing time, and difficulty in removing grinding damage caused by previous processing. At the same time, silica sol-based fine polishing solutions are prone to crystallization and precipitation, making them difficult to store and reducing their service life.

[0004] To address the aforementioned issues, it is of great significance to develop a high-efficiency, stable fine polishing fluid that achieves excellent surface roughness, combines polishing surface quality and polishing efficiency, and reduces processing costs. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention uses silica sol of different particle sizes to prepare irregular composite abrasives, and combines them with various additives to improve the dual effects of chemical oxidation and mechanical friction, so as to obtain a fine polishing fluid with high polishing efficiency and high flatness treatment.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a silicon carbide polishing slurry containing composite silica sol abrasive, comprising the following components by mass percentage: 1%-20% composite silica sol abrasive, 0.01%-1% dispersant, 0.1%-10% oxidant, 1%-20% auxiliary oxidant, 0.001%-0.1% pH adjuster, and the remainder being deionized water; wherein the composite silica sol abrasive comprises at least two types of silica sol with a particle size difference of more than 50 nm.

[0008] In some embodiments of the present invention, the particle size of the silica sol is 15-130 nm.

[0009] In some embodiments of the present invention, the pH of the silicon carbide polishing slurry is 6.0-7.0.

[0010] In some embodiments of the present invention, the composite silica sol abrasive is composed of 30%-88% silica sol with a particle size of 80 nm and 12%-70% silica sol with a particle size of 130 nm, based on the total mass of the composite silica sol abrasive; the dispersant accounts for 0.1% of the mass of the silicon carbide polishing slurry.

[0011] In some embodiments of the present invention, the composite silica sol abrasive, based on the total mass of the composite silica sol abrasive, comprises 2%-25% silica sol with a particle size of 15 nm, 30%-75% silica sol with a particle size of 80 nm, and 12%-63% silica sol with a particle size of 130 nm; the dispersant accounts for 0.5% of the mass of the silicon carbide polishing slurry.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned silicon carbide polishing slurry containing composite silica sol abrasive, comprising the following steps:

[0013] Step 1: Mix silica sols of different particle sizes evenly to obtain composite silica sol abrasives;

[0014] Step 2: Add dispersant, oxidant, auxiliary oxidant and deionized water to the composite silica sol abrasive in sequence, mix well, and add pH adjuster to adjust the pH to 6.0-7.0 to obtain silicon carbide polishing slurry.

[0015] The third aspect of the present invention provides the application of the silicon carbide polishing slurry containing the above-mentioned composite silica sol abrasive in chemical mechanical polishing.

[0016] In some embodiments of the present invention, it is applicable to silicon carbide wafer polishing.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The silicon carbide polishing slurry containing composite silica sol abrasive provided by this invention enhances the frictional effect of polishing by adjusting silica sol of different particle sizes in a specific ratio, achieving both high polishing rate and high surface quality. Furthermore, the composite abrasive is optimized, and the silica sol with the optimal compounding ratio is selected to prepare the silicon carbide polishing slurry. The slight agglomeration of the abrasive at the composite particle size is controlled to ensure that the silica sol is uniform and free from gelation, forming irregular linear and chain-like silica sols, which effectively increases the interfacial friction coefficient during polishing. The synergistic addition of a quantitative regulator forms a uniformly dispersed composite abrasive fine polishing slurry, greatly improving polishing efficiency.

[0019] 2. The silicon carbide polishing slurry containing composite silica sol abrasive provided by the present invention optimizes the amount of dispersant to ensure uniform dispersion of the composite silica sol abrasive. At the same time, the chemical oxidation effect of the dispersant and the co-oxidant works synergistically to form a composite abrasive fine polishing slurry, which greatly improves the polishing efficiency.

[0020] 3. Compared with single-abrasive silicon carbide polishing fluid, the silicon carbide polishing fluid provided by the present invention contains composite particle size silica sol abrasive, which can enhance the mechanical friction points and wear resistance of silicon carbide polishing fluid. At the same time, the polishing process is less likely to cause scratches and damage layers on the wafer surface, resulting in low surface roughness. Attached Figure Description

[0021] Figure 1 This is a SEM image of the silicon carbide polishing slurry containing composite silica sol abrasive provided in Embodiment 2 of the present invention. Detailed Implementation

[0022] The following details the silicon carbide polishing slurry containing composite silica sol abrasive, its preparation method, and its applications.

[0023] The inventors of this invention enhanced the frictional effect of polishing by adjusting silica sols of different particle sizes in a specific ratio, and synergistically added a specific amount of dispersant to control the slight agglomeration of abrasives with composite particle sizes, forming irregular linear and chain-shaped silica sols. The pH range of the polishing slurry was adjusted. The above features worked synergistically, and the friction coefficient of the polishing slurry at the silicon carbide interface was significantly improved. Based on this, the invention was completed.

[0024] The first aspect of the present invention provides a silicon carbide polishing slurry containing composite silica sol abrasive, comprising the following components by mass percentage: 1%-20% composite silica sol abrasive, 0.01%-1% dispersant, 0.1%-10% oxidant, 1%-20% auxiliary oxidant, 0.001%-0.1% pH adjuster, and the remainder being deionized water; wherein the composite silica sol abrasive comprises at least two types of silica sol with a particle size difference of more than 50 nm.

[0025] Silica sol abrasives have a lower hardness than diamond micron powder and alumina abrasives, giving them an advantage in the fine polishing stage of silicon carbide. The particle size of the silica sol significantly affects polishing efficiency. The particle size of the abrasive in the polishing slurry affects the mechanical action of polishing. Large-diameter abrasives have a larger contact friction area and relatively stronger mechanical removal, while small-diameter abrasives can refine the surface, improve flatness, and achieve better polished surface quality, but with lower polishing efficiency. Therefore, the synergistic effect of silica sols with different particle sizes is crucial for improving polishing efficiency. Currently, commercially available silica sols have a particle size range of 20-160 nm. This invention forms irregular composite abrasives by blending silica sols with a particle size difference of more than 50 nm. At a specific ratio, this enhances the frictional action of polishing and, in combination with various additives, improves the dual effects of chemical oxidation and mechanical friction, thereby obtaining a fine polishing slurry with high polishing efficiency and high flatness treatment. In this invention, the particle size of the silica sol is 15-130 nm. The composite silica sol abrasive includes at least two silica sols with a particle size difference of more than 50 nm. For example, it can include two particle sizes of 15 nm and 80 nm, two particle sizes of 15 nm and 130 nm, two particle sizes of 80 nm and 130 nm, or three particle sizes of 15 nm, 80 nm and 130 nm, etc.

[0026] In some specific embodiments of the present invention, the pH of the silicon carbide polishing slurry is 6.0-7.0, which can be 6.0-6.5 or 6.5-7.0. In the present invention, by controlling the pH of the silicon carbide polishing slurry to be weakly acidic, the stability of the polishing slurry can be improved.

[0027] In some specific embodiments of the present invention, the composite silica sol abrasive is composed of 30%-88% silica sol with a particle size of 80 nm and 12%-70% silica sol with a particle size of 130 nm, based on the total mass of the composite silica sol abrasive.

[0028] In some specific embodiments of the present invention, the composite silica sol abrasive is composed of 2%-25% silica sol with a particle size of 15nm, 30%-75% silica sol with a particle size of 80nm, and 12%-63% silica sol with a particle size of 130nm, based on the total mass of the composite silica sol abrasive.

[0029] In some specific embodiments of the present invention, the abrasive is a spherical silica sol; in the present invention, the silica sol is prepared by ion exchange method, sol-gel method or sodium silicate hydrolysis method.

[0030] In some specific embodiments of the present invention, the dispersant is selected from any one or more of sodium hexametaphosphate, sodium tripolyphosphate, and sodium polyacrylate. Preferably, the dispersant is selected from sodium hexametaphosphate. The dispersion stability of the composite silica sol abrasive in the silicon carbide polishing solution is a key factor affecting the polished surface quality and long-term storage. During the polishing process, small-diameter silica sol fills the gaps between large-diameter silica sol particles, making it easier for flocculation and gelation to occur between silica sol particles. The present invention optimizes and screens the content of the dispersant to ensure that the composite silica sol is not prone to gelation, thereby improving the stability of the polishing solution. In some preferred embodiments of the present invention, based on the total mass of the composite silica sol abrasive, the composite silica sol abrasive consists of 30%-88% silica sol with a particle size of 80 nm and 12%-70% silica sol with a particle size of 130 nm; the dispersant accounts for 0.1% of the mass of the silicon carbide polishing solution. In some other preferred embodiments of the present invention, the composite silica sol abrasive, based on the total mass of the composite silica sol abrasive, comprises 2%-25% silica sol with a particle size of 15 nm, 30%-75% silica sol with a particle size of 80 nm, and 12%-63% silica sol with a particle size of 130 nm; the dispersant accounts for 0.5% of the mass of the silicon carbide polishing slurry.

[0031] In some specific embodiments of the present invention, the oxidant is selected from any one or more of sodium metavanadate, sodium orthovanadate, potassium metavanadate, potassium orthovanadate, ammonium metavanadate, potassium molybdate, sodium molybdate, and ammonium molybdate. Preferably, the oxidant is selected from sodium metavanadate.

[0032] In some specific embodiments of the present invention, the auxiliary oxidant is selected from any one or more of hydrogen peroxide, potassium permanganate, potassium manganate, potassium ferrate, sodium periodate, iodic acid, and potassium iodate. Preferably, the auxiliary oxidant is selected from hydrogen peroxide. In some more specific embodiments of the present invention, the auxiliary oxidant is an aqueous solution of hydrogen peroxide. Because the addition of composite particle size silica sol improves the mechanical polishing performance, hydrogen peroxide is beneficial for improving the chemical oxidation and corrosion of the silicon carbide surface with the polishing solution, thereby obtaining an optimal flatness surface.

[0033] In some specific embodiments of the present invention, the pH adjuster is selected from any one or more of nitric acid, sulfuric acid, citric acid, malic acid, tartaric acid, oxalic acid, acetic acid, potassium hydroxide, sodium hydroxide, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate. By adding the pH adjuster, the pH of the polishing solution is stabilized at 6.0-7.0, which slows down the decomposition of the auxiliary oxidant hydrogen peroxide under weakly acidic conditions and improves the service life of the polishing solution.

[0034] A second aspect of the present invention provides a method for preparing the above-mentioned silicon carbide polishing slurry containing composite silica sol abrasive, comprising the following steps:

[0035] Step 1: Mix silica sols of different particle sizes evenly to obtain composite silica sol abrasives;

[0036] Step 2: Add dispersant, oxidant, auxiliary oxidant and deionized water to the composite silica sol abrasive in sequence, mix well, and add pH adjuster to adjust the pH to 6.0-7.0 to obtain silicon carbide polishing slurry.

[0037] In some specific embodiments of the present invention, the uniform mixing is achieved by mechanical stirring.

[0038] A third aspect of this invention provides the application of the aforementioned silicon carbide polishing slurry containing composite silica sol abrasive in chemical mechanical polishing. The silicon carbide polishing slurry provided by this invention exhibits an optimal coefficient of friction and removal rate on the silicon carbide surface, achieving a removal rate of up to 230 nm / h on the silicon surface. Simultaneously, the surface roughness Ra after polishing can be reduced to below 0.1 nm, resulting in high substrate surface quality, no scratches, no organic residue, a long cycle life of the polishing slurry, and high economic benefits.

[0039] In some specific embodiments of the present invention, it is applicable to silicon carbide wafer polishing.

[0040] The following detailed description of specific embodiments of the present invention, in conjunction with preferred embodiments, further illustrates the relevant details. When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range, as well as any value between the two endpoints, may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, devices, and materials used in the embodiments, the present invention can be implemented using any prior art methods, devices, and materials similar to or equivalent to those described in the embodiments of the present invention, provided that those skilled in the art possess the prior art and the description of the present invention.

[0041] Example 1

[0042] 1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0043] 5 wt.% of silica sol with a particle size of 15 nm;

[0044] 12.5 wt.% of silica sol with a particle size of 80 nm;

[0045] 2.5 wt.% of silica sol with a particle size of 130 nm;

[0046] Dispersant sodium hexametaphosphate 0.5 wt.%;

[0047] Oxidizing agent: sodium metavanadate 5 wt.%;

[0048] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0049] pH adjuster: Nitric acid (appropriate amount);

[0050] Deionized water, replenished to 100 wt.%.

[0051] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0052] S1. Under mechanical stirring, 5 wt.% of silica sol with a particle size of 15 nm, 12.5 wt.% of silica sol with a particle size of 80 nm, and 2.5 wt.% of silica sol with a particle size of 130 nm are selected and mixed evenly to obtain abrasive.

[0053] S2. Add 0.5 wt.% dispersant sodium hexametaphosphate, 5 wt.% oxidant sodium metavanadate, 5 wt.% auxiliary oxidant (30% hydrogen peroxide solution) and deionized water to the obtained abrasive in sequence, mix well, and add a few drops of nitric acid to adjust the pH value of the polishing solution to 6.0-7.0 to obtain a silicon carbide polishing solution with an average particle size of 100 nm.

[0054] Example 2

[0055] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0056] 0.5 wt.% of silica sol with a particle size of 15 nm;

[0057] 15 wt.% of silica sol with a particle size of 80 nm;

[0058] 4.5 wt.% of silica sol with a particle size of 130 nm;

[0059] Dispersant sodium hexametaphosphate 0.5 wt.%;

[0060] Oxidizing agent: sodium metavanadate 5 wt.%;

[0061] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0062] pH adjuster: Nitric acid (appropriate amount);

[0063] Deionized water, replenished to 100 wt.%.

[0064] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0065] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0066] Figure 1This is a SEM image of the silicon carbide polishing slurry containing composite silica sol abrasive prepared in this embodiment. Figure 1 It can be seen that, due to the different van der Waals forces and electrostatic repulsion between silica sols of different particle sizes, some silica sols agglomerate to form linear, chain-like particles and irregular non-spherical particles.

[0067] Example 3

[0068] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0069] 1.5 wt.% of silica sol with a particle size of 15 nm;

[0070] 6 wt.% silica sol with a particle size of 80 nm;

[0071] 12.5 wt.% of silica sol with a particle size of 130 nm;

[0072] Dispersant sodium hexametaphosphate 0.5 wt.%;

[0073] Oxidizing agent: sodium metavanadate 5 wt.%;

[0074] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0075] pH adjuster: Nitric acid (appropriate amount);

[0076] Deionized water, replenished to 100 wt.%.

[0077] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0078] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0079] Example 4

[0080] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0081] 17.5 wt.% of silica sol with a particle size of 80 nm;

[0082] 2.5 wt.% of silica sol with a particle size of 130 nm;

[0083] Dispersant sodium hexametaphosphate 0.1 wt.%;

[0084] Oxidizing agent: sodium metavanadate 5 wt.%;

[0085] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0086] pH adjuster: Nitric acid (appropriate amount);

[0087] Deionized water, replenished to 100 wt.%.

[0088] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0089] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0090] Example 5

[0091] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0092] 15.5 wt.% of silica sol with a particle size of 80 nm;

[0093] 4.5 wt.% of silica sol with a particle size of 130 nm;

[0094] Dispersant sodium hexametaphosphate 0.1 wt.%;

[0095] Oxidizing agent: sodium metavanadate 5 wt.%;

[0096] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0097] pH adjuster: Nitric acid (appropriate amount);

[0098] Deionized water, replenished to 100 wt.%.

[0099] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0100] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0101] Example 6

[0102] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0103] 6 wt.% silica sol with a particle size of 80 nm;

[0104] 14 wt.% of silica sol with a particle size of 130 nm;

[0105] Dispersant sodium hexametaphosphate 0.1 wt.%;

[0106] Oxidizing agent: sodium metavanadate 5 wt.%;

[0107] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0108] pH adjuster: Nitric acid (appropriate amount);

[0109] Deionized water, replenished to 100 wt.%.

[0110] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0111] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0112] Example 7

[0113] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0114] 0.5 wt.% of silica sol with a particle size of 15 nm;

[0115] 15 wt.% of silica sol with a particle size of 80 nm;

[0116] 4.5 wt.% of silica sol with a particle size of 130 nm;

[0117] Dispersant sodium hexametaphosphate 0.1 wt.%;

[0118] Oxidizing agent: sodium metavanadate 5 wt.%;

[0119] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0120] pH adjuster: Nitric acid (appropriate amount);

[0121] Deionized water, replenished to 100 wt.%.

[0122] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0123] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0124] Example 8

[0125] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0126] 0.5 wt.% of silica sol with a particle size of 15 nm;

[0127] 15 wt.% of silica sol with a particle size of 80 nm;

[0128] 4.5 wt.% of silica sol with a particle size of 130 nm;

[0129] Dispersant sodium hexametaphosphate 0.8 wt.%;

[0130] Oxidizing agent: sodium metavanadate 5 wt.%;

[0131] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0132] pH adjuster: Nitric acid (appropriate amount);

[0133] Deionized water, replenished to 100 wt.%.

[0134] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0135] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0136] Example 9

[0137] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0138] 1.5 wt.% of silica sol with a particle size of 15 nm;

[0139] 6 wt.% silica sol with a particle size of 80 nm;

[0140] 12.5 wt.% of silica sol with a particle size of 130 nm;

[0141] Dispersant sodium hexametaphosphate 0.1 wt.%;

[0142] Oxidizing agent: sodium metavanadate 5 wt.%;

[0143] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0144] pH adjuster: Nitric acid (appropriate amount);

[0145] Deionized water, replenished to 100 wt.%.

[0146] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0147] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0148] Example 10

[0149] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0150] 1.5 wt.% of silica sol with a particle size of 15 nm;

[0151] 6 wt.% silica sol with a particle size of 80 nm;

[0152] 12.5 wt.% of silica sol with a particle size of 130 nm;

[0153] Dispersant sodium hexametaphosphate 0.8 wt.%;

[0154] Oxidizing agent: sodium metavanadate 5 wt.%;

[0155] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0156] pH adjuster: Nitric acid (appropriate amount);

[0157] Deionized water, replenished to 100 wt.%.

[0158] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0159] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0160] Example 11

[0161] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0162] 15.5 wt.% of silica sol with a particle size of 80 nm;

[0163] 4.5 wt.% of silica sol with a particle size of 130 nm;

[0164] Dispersant sodium hexametaphosphate 0.5 wt.%;

[0165] Oxidizing agent: sodium metavanadate 5 wt.%;

[0166] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0167] pH adjuster: Nitric acid (appropriate amount);

[0168] Deionized water, replenished to 100 wt.%.

[0169] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0170] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0171] Example 12

[0172] (1) The raw material composition of the silicon carbide polishing slurry containing composite silica sol abrasive is as follows:

[0173] 6 wt.% silica sol with a particle size of 80 nm;

[0174] 14 wt.% of silica sol with a particle size of 130 nm;

[0175] Dispersant sodium hexametaphosphate 0.5 wt.%;

[0176] Oxidizing agent: sodium metavanadate 5 wt.%;

[0177] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0178] pH adjuster: Nitric acid (appropriate amount);

[0179] Deionized water, replenished to 100 wt.%.

[0180] (2) Preparation of silicon carbide polishing slurry containing composite silica sol abrasive

[0181] The preparation method of the silicon carbide polishing slurry containing composite silica sol abrasive is the same as in Example 1.

[0182] Comparative Example 1

[0183] (1) The silicon carbide polishing solution of the comparative example, which uses silica sol abrasive with a particle size of 15 nm, has the following composition:

[0184] 20 wt.% of silica sol with a particle size of 15 nm;

[0185] Dispersant sodium hexametaphosphate 0.1 wt.%;

[0186] Oxidizing agent: sodium metavanadate 5 wt.%;

[0187] The auxiliary oxidant is 5 wt.% hydrogen peroxide (30% hydrogen peroxide solution);

[0188] pH adjuster: Nitric acid (appropriate amount);

[0189] Deionized water, replenished to 100 wt.%.

[0190] (2) The preparation method is as follows:

[0191] Under mechanical stirring, 20 wt.% of silica sol with a particle size of 15 nm, 0.1 wt.% of dispersant sodium hexametaphosphate, 5 wt.% of oxidant sodium metavanadate, 5 wt.% of auxiliary oxidant (30% hydrogen peroxide solution), and deionized water were added sequentially. After mixing evenly, a few drops of nitric acid were added to adjust the pH of the polishing solution to a range of 6.0-7.0, thus obtaining a silicon carbide fine polishing solution with a particle size of 15 nm.

[0192] Comparative Example 2

[0193] Except for the silica sol, which is a single silica sol with a particle size of 80 nm, the rest are the same as in Comparative Example 1.

[0194] Comparative Example 3

[0195] Except for the silica sol, which is a single silica sol with a particle size of 90 nm, the rest are the same as in Comparative Example 1.

[0196] Comparative Example 4

[0197] Except for the silica sol, which is a single silica sol with a particle size of 100 nm, the rest are the same as in Comparative Example 1.

[0198] Comparative Example 5

[0199] Except for the silica sol, which is a single silica sol with a particle size of 130 nm, the rest are the same as in Comparative Example 1.

[0200] Comparative Example 6

[0201] Except for the dispersant sodium hexametaphosphate, which has a mass fraction of 0.005 wt.%, the rest is the same as in Example 2.

[0202] Comparative Example 7

[0203] Except for the dispersant sodium hexametaphosphate, which has a mass fraction of 0.005 wt.%, the rest is the same as in Example 3.

[0204] Comparative Example 8

[0205] Except for the dispersant sodium hexametaphosphate, which has a mass fraction of 0.005 wt.%, the rest is the same as in Example 5.

[0206] Comparative Example 9

[0207] Except for the dispersant sodium hexametaphosphate, which has a mass fraction of 0.005 wt.%, the rest is the same as in Example 6.

[0208] (I) Performance comparison of composite silica sol abrasive and single-particle-size silica sol abrasive silicon carbide polishing slurry The components of the silicon carbide polishing slurries prepared in Examples 1-6 and Comparative Examples 1-5 are shown in Table 1 below.

[0209] Table 1

[0210]

[0211] The interfacial friction coefficients of the silicon carbide polishing slurries prepared in Examples 1-6 and Comparative Examples 1-5 were tested.

[0212] The microcomputer-controlled vertical friction and wear tester, manufactured by Jinan Yister Test Instrument Equipment Co., Ltd., uses SiC as the friction object, a polishing pad with a Shore hardness of 50A as the friction substrate, and polishing slurry as the friction medium. During testing, the machine automatically collects and records data such as the coefficient of friction and frictional force. In the testing process, the surface of the silicon carbide wafer is brought into contact with one side of the polishing pad, and polishing slurry is poured into the test sample cell. The silicon carbide wafer and polishing pad are kept rotating horizontally and completely immersed in the polishing slurry sample cell. The silicon carbide wafer rotates at 60 rpm, the pressure is 80 N, and the test time is 10 minutes. After each test, the silicon carbide wafer and polishing pad are ultrasonically cleaned in deionized water for 10 minutes to remove any residual polishing slurry.

[0213] The specific test process parameters are shown in Table 2 below:

[0214] Table 2

[0215] Friction object: 4-inch silicon carbide wafer Friction surface: (0001)-Si surface Application method: Solid wax Friction substrate: polishing pad Medium: Polishing slurry Time: 10 min Pressure: 80N Speed: 60 rpm

[0216] The interfacial friction force and coefficient of friction between the polishing slurry and silicon carbide are shown in Table 3 below:

[0217] Table 3

[0218]

[0219]

[0220] Material removal rate tests were conducted on the silicon carbide polishing slurries prepared in Examples 1-6 and Comparative Examples 1-5: The material removal rate of the silicon carbide wafers was calculated using the weighing method. The polishing pad material used had a Shore hardness of 50A and a compression ratio of 10%. During the test, the polishing slurry was always mechanically stirred to ensure uniform dispersion of the abrasive and uniform flow of the polishing slurry.

[0221] The specific polishing process parameters are shown in Table 4 below:

[0222] Table 4

[0223]

[0224] The removal rate and surface roughness data of the silicon carbide polishing slurry are shown in Table 5 below:

[0225] Table 5

[0226]

[0227]

[0228] Based on the data from Examples 1-6 and Comparative Examples 1-5, it can be seen that the silicon carbide polishing slurry prepared by the present invention, containing composite silica sol abrasive, enhances the polishing friction by adjusting silica sol of different particle sizes in a specific ratio. The addition of a specific amount of dispersant controls the slight agglomeration of the abrasive with composite particle sizes, forming irregular linear and chain-like silica sols. Adjusting the pH range of the polishing slurry also contributes to the synergistic effect of these characteristics, significantly improving the friction coefficient at the silicon carbide interface. In Examples 1-6, the polishing slurries with composite silica sol exhibit higher interfacial friction and a higher friction coefficient. Compared to silicon carbide polishing slurries with single particle sizes (Comparative Examples 1-5), the removal rate on the silicon surface is higher, and the surface roughness is lower and smoother. Example 2 demonstrates the best removal efficiency, achieving a removal rate of 230 nm / h on the silicon surface, while simultaneously reducing the surface roughness to 0.06 nm after polishing. This proves that the composite silica polishing slurry has higher processing efficiency and superior performance, combining both high polishing rate and high surface quality.

[0229] (II) The effect of the mass percentage of dispersant on the performance of silicon carbide polishing slurry

[0230] The removal rate of the silicon carbide polishing slurries prepared in Examples 2, 3, 5-12 and Comparative Examples 6-9 was tested using the same method as above. The test results are shown in Table 6 below:

[0231] Table 6

[0232]

[0233]

[0234] Table 6 shows that Examples 1-3, which are silicon carbide polishing solutions with three composite particle sizes, showed no gelation or foaming when 0.5% sodium hexametaphosphate was added, and exhibited the best silicon surface removal rate. Examples 7 and 9, which are silicon carbide polishing solutions with three composite particle sizes, showed slight foaming during preparation with 0.1% sodium hexametaphosphate, and the silicon surface removal rate was lower than that of Examples 2 and 3. This may be because insufficient sodium hexametaphosphate led to agglomeration and gelation of the composite abrasive, affecting polishing efficiency. Examples 8 and 10, which are silicon carbide polishing solutions with three composite particle sizes, showed no gelation or foaming during preparation, but the silicon surface removal rate was lower than that of Examples 2 and 3. This is presumably because excessive sodium hexametaphosphate caused free sodium hexametaphosphate to form micelles, reducing the polishing removal rate. Examples 4-6, which are silicon carbide polishing solutions with two composite particle sizes, showed the best dispersion effect and good silicon surface removal rate when 0.1% sodium hexametaphosphate was added. Examples 11 and 12 show two composite particle size silicon carbide polishing solutions with the addition of 0.5% sodium hexametaphosphate. No gelation or foaming occurred, but the silicon surface removal rate was lower than in Examples 5 and 6. This is presumably because excessive addition led to the formation of micelles from free sodium hexametaphosphate, reducing the polishing removal rate. Comparative Examples 6-9, with the addition of 0.005% sodium hexametaphosphate, exhibited gelation during preparation, indicating that insufficient sodium hexametaphosphate resulted in poor dispersion of the polishing solution. In conclusion, the particle size distribution of the composite silica sol is interrelated with the amount of dispersant used; specific amounts of dispersant are required to ensure both effective dispersion and silicon surface removal rate of the polishing solution.

[0235] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A silicon carbide polishing liquid containing a composite silica sol abrasive, characterized by, The silicon carbide polishing liquid comprises the following components by mass percentage: composite silica sol abrasive 1-20%, dispersant 0.01-1%, oxidant 0.1-10%, auxiliary oxidant 1-20%, pH regulator 0.001-0.1%, and the rest is deionized water; the pH of the silicon carbide polishing liquid is 6.0-7.0; the dispersant is selected from sodium hexametaphosphate; the oxidant is selected from sodium metavanadate; the auxiliary oxidant is selected from hydrogen peroxide; the composite silica sol abrasive consists of 30-88% silica sol with a particle size of 80 nm and 12-70% silica sol with a particle size of 130 nm, based on the total mass of the composite silica sol abrasive; the mass percentage of the dispersant in the silicon carbide polishing liquid is 0.1%; or the composite silica sol abrasive consists of 2-25% silica sol with a particle size of 15 nm, 30-75% silica sol with a particle size of 80 nm and 12-63% silica sol with a particle size of 130 nm, based on the total mass of the composite silica sol abrasive; the mass percentage of the dispersant in the silicon carbide polishing liquid is 0.5%.

2. The silicon carbide polishing slurry containing a composite silica sol abrasive according to claim 1, wherein One or more of the following features are included: (1) the silica sol is spherical silica sol; (2) the pH regulator is selected from any one or more of nitric acid, sulfuric acid, citric acid, malic acid, tartaric acid, oxalic acid, acetic acid, potassium hydroxide, sodium hydroxide, dipotassium hydrogen phosphate, potassium dihydrogen phosphate.

3. The silicon carbide polishing slurry containing a composite silica sol abrasive according to claim 2, wherein The silica sol is prepared by ion exchange method, sol-gel method or sodium silicate hydrolysis method.

4. A method for preparing a silicon carbide polishing slurry containing a composite silica sol abrasive according to any one of claims 1 to 3, characterized by, The following steps are included: Step one: uniformly mix silica sols with different particle sizes to obtain composite silica sol abrasive; Step two: add dispersant, oxidant, auxiliary oxidant and deionized water to the composite silica sol abrasive in sequence, mix uniformly, add pH regulator to adjust the pH to 6.0-7.0, and the silicon carbide polishing liquid is obtained.

5. The method of preparing a silicon carbide polishing slurry containing a composite silica sol abrasive according to claim 4, characterized by, The uniform mixing is achieved by mechanical stirring.

6. Use of the silicon carbide polishing liquid containing composite silica sol abrasive according to any one of claims 1-3 or prepared by the preparation method of claims 4 or 5 in chemical mechanical polishing.

7. Use according to claim 6, wherein It is suitable for polishing of silicon carbide wafers. It is suitable for polishing of silicon carbide wafers.

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