Controllable synthesis of core-shell SiO2@CeO2 composite abrasives for chemical mechanical polishing of EMC-Si-Cu multi-heterointerfaces

Abstract

With the development of advanced electronic packaging, a big challenge for the chemical mechanical polishing (CMP) is to achieve the global planarization of EMC (epoxy molding compound)-Si-Cu materials with the normal ceramic abrasives. In this paper, the SiO₂@CeO₂ core-shell composite abrasive is developed for the CMP of EMC/Si/Cu materials for the first time, and a global planarization with low removal selectivity is expected owing to the synergistic effect of the core-shell abrasives. Two sol-gel synthetic strategies, i.e., oil bath and ultrasonication, are proposed for the controllable synthesis of the SiO₂@CeO₂ abrasives, which exhibit a good dispersive stability with a large absolute zeta potential >30 mV. The slurry for the CMP of EMC-Si-Cu based on the SiO₂@CeO₂ abrasives shows the advantage in controlling the surface roughness, material removal rate and the removal selectivity. Especially, the ultrasonic SiO₂@CeO₂ abrasives give rise to the low surface roughness (Cu 2 nm, Si 0.3 nm, EMC 10 nm) and the low removal selectivity (Cu/EMC/Si = 1.58:1.56:1.00). Therefore, the proposed SiO₂@CeO₂ core-shell abrasives and the developed CMP slurry opens an alternative way for the planarization of EMC/Si/Cu materials in the advanced electronic packaging.