Atomistic insights into shell-modulated interfacial interactions of core-shell SiO2@organic polymer abrasives for silicon chemical mechanical polishing.

Understanding how core-shell abrasive architecture governs interfacial interactions is critical for balancing material removal rate (MRR) and surface quality in chemical mechanical polishing (CMP). Here, a core-shell abrasive system with a SiO2 core and an organic shell is investigated through an integrated approach combining polishing experiments, physicochemical characterization, and multiscale molecular dynamics (MD) simulations. Polishing experiments on single-crystal silicon demonstrate that a thin organic shell significantly improves surface quality while reducing MRR, suggesting that the organic shell suppresses aggressive mechanical interaction at the abrasive-substrate interface. MD simulations reveal a non-monotonic dependence of particle-substrate adhesion on shell thickness. A single organic layer markedly enhances adhesion by positioning interfacial atoms within the energetically favorable van der Waals interaction distance, whereas further shell thickening reduces adhesion due to increased interfacial separation and electrostatic screening. Atomic force microscopy (AFM) measurements provide experimental evidence for the enhanced adhesion in the thin-shell regime. Reactive MD (RMD) simulations further show that the organic shell acts as a compliant buffer that redistributes contact stress, mitigates localized deformation, and significantly reduces defect generation, promoting a transition from defect-dominated removal to a more uniform and controlled process. The experimentally observed shell thickness (approximately 1.38 nm) coincides with the regime where adhesion enhancement and mechanical compliance are optimally coupled. These findings reveal the structure-property relationship governing polishing behavior and provide rational design principles for high-performance core-shell abrasives.