Effects of process parameters on chemical-mechanical interactions during sapphire polishing

Abstract

This paper investigated the influences of process parameters on sapphire MRR and polished surface quality during ultrasonic flexural vibration assisted chemical mechanical polishing (UFV-CMP). Sapphire removing and planarization mechanisms of process parameters during UFV-CMP were explored as well. Orthogonal experiments' results and variance analyses showed that the polishing pressure and rotating speed are the major factors to remove sapphire material. Moreover, the polishing pressure is the most important parameter to decrease the sapphire surface's roughness. The increasing polishing pressure and rotating speed not only enhanced the mechanical abrasion but also accelerated the chemical reactions during sapphire UFV-CMP. The chemical-mechanical interactions during sapphire UFV-CMP balanced under certain conditions and obtained high MRR and lowest roughness simultaneously. The optimal process parameters were 7.0 psi pressure and 80 rpm rotating speed. The corresponding sapphire MRR and polished surface roughness were 3.1 μm/h and 0.1 nm respectively. This investigation is beneficial to revealing the polishing mechanism and optimizing the process of sapphire UFV-CMP.