Mechanistic insights into the synergistic effect of oxidizers and abrasives in chemical mechanical polishing of 4H-SiC wafer

Abstract

Abrasive and oxidizer components in chemical mechanical polishing (CMP) slurries play a critical role in determining polishing efficiency, surface quality, and material removal mechanisms , especially for hard and brittle materials such as silicon carbide (SiC). However, existing studies often focus on single-component optimization or empirical slurry development. Thus, there is limited understanding of abrasive–oxidizer interactions and their synergistic effects on polishing performance. In this work, a high-performance SiC CMP slurry was developed through systematic investigation of four abrasives (diamond, SiO 2 , CeO 2 , and Al 2 O 3 ) and four oxidizers (KMnO 4 , H 2 O 2 , KIO 4 , and K 2 S 2 O 8 ). Among all abrasive-oxidizer combinations, Al 2 O 3 abrasive and KMnO 4 oxidizer exhibited the best synergistic effect. To further enhance polishing performance, an orthogonal experimental design was employed to optimize slurry formulation and process parameters. Material removal rate (MRR) of 1398 nm/h and surface roughness (S a ) of 0.117 nm were achieved under these optimized conditions. X-ray photoelectron spectroscopy (XPS) was used to analyze the surface chemistry and material removal mechanism. The results indicate that under mechanical stress, Al 2 O 3 abrasives generate localized frictional heat and chemically interact with the oxidized SiC surface, forming an Al–O–Si interfacial layer . This transient layer acts as a soft sacrificial layer that is continuously formed and sheared off during polishing, enabling efficient and damage-free material removal. This study provides a mechanistic understanding of abrasive–oxidizer synergy in SiC CMP and establishes a practical framework for the design of slurries with enhanced performance, offering valuable guidance for precision processing of advanced ceramic materials .

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