Photochemical-Co-Mechanical Polishing for Silicon Wafer Using a Janus CeO2 Slurry

Abstract Chemical mechanical polishing (CMP) faces the inherent challenge of increasing the material removal rate (MRR) while maintaining an ultralow surface roughness. In this work, we report a Janus CeO2 slurry for photochemical-co-mechanical polishing (PCMP) of Si wafers. It achieves an MRR of 585.8 nm/min while maintaining an ultralow root mean square roughness of 0.043 nm and a peak-to-valley value of 0.173 nm, which approaches the theoretical limit for Si(100) surfaces of 0.136 nm. The "Janus" CeO2 slurry acts as both a semiconductor photocatalyst, generating superoxide radicals to accelerate oxidation of the Si wafer, and a mechanical abrasive facilitating construction of Ce–O–Si bonds through Ce3+ ions, thereby mechanically removing the oxide layer of Si and simultaneously accelerating the PCMP process. This study demonstrates a novel strategy for integrating photocatalysis into CMP processes involving oxidation reactions, offering promising potential for advanced planarization applications.