Highly efficient removal of sapphire by composite nanoabrasive with novel inorganic polyelectrolyte as a binder

Chemical mechanical polishing has shown great prospect in a wide range of microelectronics applications due to the global planarization. For the first time, we proposed a novel branched inorganic polyelectrolyte as an effective binder to modify colloidal silica. The composite abrasives combine the advantages of both colloidal silica and polyelectrolyte, exhibiting good dispersibility, stability in water and outstanding polishing property. The results indicated that the composite abrasive could enhance the material removal rate (MRR) of sapphire wafer up to 23.76%. The optimum removal rate by composite abrasive also yielded a superior surface roughness (Ra) of 1.445 nm. The mechanism between the composite abrasives and sapphire in chemical mechanical polishing process was investigated in detail. X-ray photoelectron spectroscopy test demonstrated that a soft layer was formed on the surface of sapphire. Micro-contact model revealed that the inorganic polyelectrolyte adhered to the surface of colloidal silica could reduce the repulsion between particles and sapphire, thereby accelerating chemical-mechanical reaction rate and achieving rapid surface removal of the sapphire surface. [Display omitted] •The novel inorganic polyelectrolyte is firstly used as a binder to modify SiO2.•The polyelectrolyte-SiO2 abrasive exhibits excellent MRR and low Ra on sapphire.•Solid-state chemical reaction between abrasives and sapphire was analyzed by XPS.•Micro-contact model was used to explain the mechanism in detail.