Preparation of -alumina/silica core-shell abrasives and their chemical mechanical polishing performances on sapphire substrates

The chemical mechanical polishing (CMP) process has become a widely accepted global planarisation technology. The abrasive is one of the important influencing factors during the CMP process. In this work, -alumina/silica abrasives with a core-shell structure were synthesised. Time-of-flight secondary ion mass spectroscopy was used to characterise the composition of the obtained abrasives. The morphology and structure of the abrasives were measured by using scanning electron microscopy and transmission electron microscopy. The CMP performances of the -alumina/silica abrasives on sapphire substrates were investigated. Experimental results indicate that the -alumina/silica abrasives exhibit lower surface roughness and higher material removal rate than that of pure silica and -alumina abrasives under the same testing conditions. Furthermore, through the X-ray photoelectron spectroscopy test, this work investigated the chemical effect mechanism of the -alumina/silica core-shell abrasives in sapphire CMP. The results show that solid-state chemical reactions occur between the silica shell and sapphire surface during the CMP process. The study also established a wear model to investigate the mechanical friction mechanism.