The planarization of silicon carbide (SiC), crucial for manufacturing power devices resilient to harsh working environments, has garnered significant attention. The utilization of titanium dioxide (TiO₂)-based heterogeneous photocatalysts offers a promising avenue for achieving efficient polishing on SiC surface through photocatalysis-assisted chemical mechanical polishing (P-CMP) in an environmentally friendly manner. In this study, we employed nanodiamonds (NDs) and graphene oxide (GO) to fabricate the composite abrasive TiO₂/NDs/GO. Subsequently, the P-CMP performance of TiO₂/NDs/GO on the Si-face of SiC was systematically investigated. The high-resolution transmission electron microscopy (TEM) revealed the heterostructure between TiO₂ and NDs. Furthermore, P-CMP results indicate that the heterostructure significantly enhances the polishing rate of the composite abrasives on SiC, achieving the highest material removal rate (MRR) of 600 nm/h and reducing the average surface roughness (Sa) to 1.1705 nm. Additionally, due to the lubricating and dispersing effects of GO, the occurrence of NDs aggregation is avoided, preventing scratching on SiC. The measurement of ·OH concentration indicates that the increase in ·OH concentration is the primary factor contributing to the improvement of the MRR. Results from wetting angle and friction coefficient tests reveal that the polishing slurry containing TiO₂/NDs/GO exhibits excellent wettability and provides sufficient frictional force on the SiC surface. X-ray photoelectron spectroscopy (XPS) characterization demonstrates that TiO₂/NDs/GO enhances the oxidation degree of the SiC surface, leading to the formation of a softer oxide layer. Finally, based on experimental and characterization results, a comprehensive analysis of TiO₂/NDs/GO and P-CMP was conducted.

The material loss caused by bubble collapse during the micro-nano bubbles auxiliary chemical mechanical polishing (CMP) process cannot be ignored. In this study, the material removal mechanism of cavitation in the polishing process was investigated in detail. Based on the mixed lubrication or thin film lubrication, bubble–wafer plastic deformation, spherical indentation theory, Johnson–Cook (J–C) constitutive model, and the assumption of periodic distribution of pad asperities, a new model suitable for micro-nano bubble auxiliary material removal in CMP was developed. The model integrates many parameters, including the reactant concentration, wafer hardness, polishing pad roughness, strain hardening, strain rate, micro-jet radius, and bubble radius. The model reflects the influence of active bubbles on material removal. A new and simple chemical reaction method was used to form a controllable number of micro-nano bubbles during the polishing process to assist in polishing silicon oxide wafers. The experimental results show that micro-nano bubbles can greatly increase the material removal rate (MRR) by about 400% and result in a lower surface roughness of 0.17 nm. The experimental results are consistent with the established model. In the process of verifying the model, a better understanding of the material removal mechanism involved in micro-nano bubbles in CMP was obtained.

The chemical mechanical polishing (CMP) process has become a widely accepted global planarization technology. The abrasive material is one of the key elements in CMP. In the presented paper, an Ag-doped colloidal SiO₂ abrasive is synthesized by a seed-induced growth method. It is characterized by time-of-flight secondary ion mass spectroscopy and scanning electron microscopy to analyze the composition and morphology. The CMP performance of the Ag-doped colloidal silica abrasives on sapphire substrates is investigated. Experiment results show the material removal rate (MRR) of Ag-doped colloidal silica abrasives is obviously higher than that of pure colloidal silica abrasives under the same testing conditions. The surfaces that are polished by composite colloidal abrasives exhibit lower surface roughness (Ra) than those polished by pure colloidal silica abrasives. Furthermore, the acting mechanism of Ag-doped colloidal SiO₂ composite abrasives in sapphire CMP is analyzed by X-ray photoelectron spectroscopy, and analytical results show that element Ag forms Ag₂O which acts as a catalyst to promote the chemical effect in CMP and leads to the increasing of MRR.

The effect of tert-butyl hydroperoxide-sodium pyrosulfite ((CH₃)₃COOH-Na₂S₂O₅) as an initiator system in H₂O₂-based slurry was investigated for the abrasive-free polishing (AFP) of a hard disk substrate. The polishing results show that the H₂O₂-C₄H₁₀O₂-Na₂S₂O₅ slurry exhibits a material removal rate (MRR) that is nearly 5 times higher than that of the H₂O₂ slurry in the AFP of the hard disk substrate. In addition, the surface polished by the slurry containing the initiator exhibits a lower surface roughness and has fewer nano-asperity peaks than that of the H₂O₂ slurry. Further, we investigate the polishing mechanism of H₂O₂-C₄H₁₀O₂-Na₂S₂O₅ slurry. Electron spin-resonance spectroscopy and auger electron spectrometer analyses show that the oxidizing ability of the H₂O₂-C₄H₁₀O₂-Na₂S₂O₅ slurry is much greater than that of the H₂O₂ slurry. The results of potentiodynamic polarization measurements show that the hard disk substrate in the H₂O₂-C₄H₁₀O₂-Na₂S₂O₅ slurry can be rapidly etched, and electrochemical impedance spectroscopy analysis indicates that the oxide film of the hard disk substrate formed in the H₂O₂-C₄H₁₀O₂-Na₂S₂O₅ slurry may be loose, and can be removed easily during polishing. The better oxidizing and etching ability of H₂O₂-C₄H₁₀O₂-Na₂S₂O₅ slurry leads to a higher MRR in AFP for hard disk substrates.