Effects of Different Dispersants on Chemical Reaction and Material Removal in Ultrasonic Assisted Chemical Mechanical Polishing of Sapphire

Abstract

Effects of different dispersing reagents on ultrasonic assisted chemical mechanical polishing (UV-CMP) of sapphire were investigated in this study. Their influences on chemical reaction and mechanical action between silica particles and sapphire surface were explored by X-ray photoelectron spectroscopy, scanning electron microscope, zeta potential and particle size analyses. The results show that ultrasonic and polyethylene glycol can synergistically promote the chemical reaction and sapphire removal rate. However, sodium polyacrylate and sodium hexametaphosphate will inhibit the chemical reaction. For different concentrations of polyethylene glycol, they affect the chemical reaction and mechanical removal due to the particle aggregation or dispersion in sapphire UV-CMP. When the content is 0.2%, the synergistic effects of chemical and mechanical action between abrasives and sapphire surface are optimal. The sapphire removal rate reaches 48.5 nm min−1 and the polished surface roughness is 0.16 nm.