A chemical mechanical polishing slurry and its application

Abstract

This invention discloses a chemical mechanical polishing slurry, comprising: nano-alumina abrasive, oxidant, catalyst, dispersant, and pH adjuster. The composition enables one-step polishing of silicon carbide substrates, improving SiC surface quality and achieving an ultra-smooth surface while maintaining a high removal rate.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing, and more particularly to a chemical mechanical polishing slurry for polishing silicon carbide. Background Technology

[0002] Third-generation semiconductor materials are mainly wide-bandgap semiconductor materials represented by silicon carbide (SiC) and gallium nitride (GaN). They have significant advantages in fields such as new energy vehicles, high-speed rail, aerospace, and communications. As a representative product of third-generation semiconductor materials, silicon carbide has characteristics such as high Mohs hardness, excellent thermal conductivity, wide bandgap, and high saturated electron mobility, and is widely used in semiconductor industry and optical devices.

[0003] Compared to traditional silicon-based devices, silicon carbide (SiC) offers significant improvements in power density, switching efficiency, and device losses. However, as a hard and brittle material, SiC possesses physical properties such as high hardness, wear resistance, oxidation resistance, and thermal stability. Therefore, polishing it presents challenges, including low efficiency, high cost, and environmental impact. For example, a silicon carbide polishing slurry (CN115975511) using cerium oxide as an abrasive can reduce scratches and surface roughness on silicon carbide substrates. However, this slurry has a low removal rate and a pH of 1-2, posing potential harm to equipment and operators. Fujimi disclosed a polishing composition and its preparation method. This composition uses silicon oxide as an abrasive and incorporates hydrogen peroxide and vanadium oxide. While this polishing slurry can achieve a smooth surface, it has a high vanadium oxide content (0.7wt%-3.5wt%) and a low polishing rate, limiting its use to fine polishing after rough polishing and impacting processing efficiency. Cabot disclosed a composition using Pt as a catalyst that can significantly improve the removal rate of single-crystal silicon carbide. However, Pt compounds are expensive and pose certain health risks.

[0004] In summary, there is a need for a silicon carbide polishing slurry that can improve the polishing rate while reducing the surface roughness of the polished substrate, minimizing scratch defects, and lowering the processing cost of silicon carbide substrates. Summary of the Invention

[0005] In order to overcome the above-mentioned technical defects, the present invention aims to provide a chemical mechanical polishing slurry that achieves one-step polishing of silicon carbide substrates during the polishing process, while maintaining a high removal rate and improving the surface quality of SiC to obtain an ultra-smooth surface.

[0006] This invention discloses a chemical mechanical polishing slurry, which includes: nano-alumina abrasive, oxidant, catalyst, dispersant and pH adjuster.

[0007] Preferably, the nano-alumina abrasive is selected from calcined α-alumina, with an α-conversion rate ≥80%.

[0008] Preferably, the oxidant is selected from one of oxone, hydrogen peroxide, potassium persulfate, and potassium permanganate.

[0009] Preferably, the concentration of the oxidant is 1 wt% to 10 wt%.

[0010] Preferably, the catalyst is selected from one or more of nitrates, sulfates, chlorides, phosphates, vanadates, and molybdates.

[0011] Preferably, the catalyst is selected from one or more of the following: nitrates, sulfates, chlorides, phosphates, vanadates, and molybdates of iron, cobalt, nickel, copper, zinc, sodium, potassium, ammonium, calcium, yttrium, zirconium, ruthenium, platinum, bismuth, cerium, rubidium, vanadium, and lanthanum.

[0012] Preferably, the concentration of the catalyst is 50-10000 ppm.

[0013] Preferably, the dispersant is selected from one or more of sodium pyrophosphate, potassium pyrophosphate, trisodium phosphate, tetrasodium phosphate, sodium hexametaphosphate, potassium metaphosphate, and potassium silicate.

[0014] Preferably, the concentration of the dispersant is 100-1000 ppm.

[0015] Preferably, the concentration of the alumina grinding particles is 1wt%-20wt%.

[0016] Preferably, the alumina grinding particles have an average particle size of 100-1000 nm.

[0017] Preferably, the pH adjuster is selected from one or more of KOH, ammonia, nitric acid, sulfuric acid, and TMAH.

[0018] Preferably, the concentration of the pH adjuster is 0.1 wt% to 5 wt%.

[0019] Preferably, the pH value of the chemical mechanical polishing solution is 2-6.

[0020] In another aspect, the present invention discloses a method for using any of the above-described chemical mechanical polishing slurries to polish silicon carbide.

[0021] Compared with existing technologies, the above technical solution has the following advantages:

[0022] 1. The catalyst has a good catalytic effect and a low catalyst content (500ppm), which can increase the removal rate by 10 times.

[0023] 2. The oxidant produces no byproducts, which can improve the surface quality of SiC and increase processing efficiency.

[0024] The composition of the present invention can achieve polishing of silicon carbide substrates in one step, while maintaining a high removal rate, improving the surface quality of SiC, obtaining an ultra-smooth surface, and improving processing efficiency and product yield. Attached Figure Description

[0025] Figure 1 The image shows the AFM images of the Si surface of SiC before and after polishing in Example 2. Detailed Implementation

[0026] The chemical mechanical polishing fluid of the present invention will be described in detail below through specific embodiments in order to better understand the present invention, but the following embodiments do not limit the scope of the present invention.

[0027] Table 1 shows Examples 1-27 and Comparative Examples 1-2 of the chemical mechanical polishing fluid of the present invention. According to the formulation given in the table, the other components except the pH adjuster are mixed evenly in sequence, and finally the pH is adjusted to the required pH value using the pH adjuster.

[0028] The reagents and raw materials used in this invention are all commercially available.

[0029] Using the polishing slurry of the embodiments and the comparative polishing slurry of the present invention, 6” single-crystal silicon carbide wafers were polished under the following conditions. The specific polishing conditions were: a CP-610 polishing machine, a Suba800 polishing pad, a polishing pressure of 4.5 psi, a polishing disc and polishing head rotation speed of 45 / 40 rpm, a polishing slurry flow rate of 500 mL / min, and a polishing time of 60 minutes.

[0030] Table 1. Components and contents of the examples and comparative examples

[0031]

[0032]

[0033] Table 1 shows that, comparing Examples 1-3 and Comparative Example 2, adding an oxidant significantly improves the removal rate. Comparing Examples 1-3, increasing the H2O2 content increases the SiC-Si removal rate, but the rate decreases significantly with further increases in H2O2 content. Comparing Examples 2 and 4-6, increasing the alumina content increases the removal rate, but further increases in alumina content significantly decrease the removal rate. Comparing Examples 2 and 7-9, the size of the alumina abrasive significantly affects the removal rate. The results of Example 2 indicate that 250 nm is the optimal abrasive size. Comparing Examples 2 and 10-12, the removal rate increases with increasing catalyst concentration. Comparing Examples 1-23 and Comparative Example 1, adding a catalyst can increase the removal rate tenfold. Comparing Examples 2 and Examples 18, 19, 24, and 25 shows that the vanadium catalyst has good catalytic effect.

[0034] from Figure 1 It can be seen that after polishing in Example 2, the SiC surface quality is good and the surface roughness is low.

[0035] This invention provides a composition for chemical mechanical polishing of silicon carbide substrates, comprising abrasive particles, an oxidant, a catalyst, a dispersant, and a pH adjuster. This composition enables one-step polishing of silicon carbide substrates, improving SiC surface quality and achieving an ultra-smooth surface while maintaining a high removal rate.

[0036] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing liquid, characterized by comprising: The polishing fluid includes: nano-alumina abrasive, oxidant, catalyst, dispersant, and pH adjuster.

2. The chemical mechanical polishing liquid according to claim 1, wherein The nano-alumina abrasive is calcined α-alumina with an α-conversion rate ≥80%.

3. The chemical mechanical polishing liquid according to claim 1, wherein The oxidant is selected from one of oxone, hydrogen peroxide, potassium persulfate, and potassium permanganate.

4. The chemical mechanical polishing liquid according to claim 1, wherein The concentration of the oxidant is 1 wt% to 10 wt%.

5. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The catalyst is selected from one or more of nitrates, sulfates, chlorides, phosphates, vanadates, and molybdates.

6. The chemical mechanical polishing slurry as described in claim 5, characterized in that, The catalyst is selected from one or more of the following: nitrates, sulfates, chlorides, phosphates, vanadates, and molybdates of iron, cobalt, nickel, copper, zinc, sodium, potassium, ammonium, calcium, yttrium, zirconium, ruthenium, platinum, bismuth, cerium, rubidium, vanadium, and lanthanum.

7. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The concentration of the catalyst is 50-10000 ppm.

8. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The dispersant is selected from one or more of sodium pyrophosphate, potassium pyrophosphate, trisodium phosphate, tetrasodium phosphate, sodium hexametaphosphate, potassium metaphosphate, and potassium silicate.

9. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The concentration of the dispersant is 100-1000 ppm.

10. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The concentration of the alumina grinding particles is 1wt%-20wt%.

11. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The alumina grinding particles have an average particle size of 100-1000 nm.

12. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The pH adjuster is selected from one or more of KOH, ammonia, nitric acid, sulfuric acid, and TMAH.

13. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The concentration of the pH adjuster is 0.1 wt% to 5 wt%.

14. The chemical mechanical polishing slurry according to any one of claims 1-13, characterized in that, The pH value of the chemical mechanical polishing fluid is 2-6.

15. A method of using the chemical mechanical polishing slurry according to any one of claims 1-14 to polish silicon carbide.

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