Effect of Abrasive Concentration on Chemical Mechanical Polishing of Sapphire

Effects of abrasive concentration on material removal rate (MRR) and surface quality in the chemical mechanical polishing (CMP) of light-emitting diode sapphire substrates are investigated. Experimental results show that the MRR increases linearly with the abrasive concentration, while the rms roughness decreases with the increasing abrasive concentration. In addition, the in situ coefficient of friction (COF) is also conducted during the sapphire polishing process. The results present that COF increases sharply with the abrasive concentration up to 20 wt% and then shows a slight decrease from 20 wt% to 40 wt%. Temperature is a product of the friction force that is proportional to COF, which is an indicator for the mechanism of the sapphire CMP.