Effect of Abrasive Concentration on Chemical Mechanical Polishing of Sapphire**Supported by the National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period under Grant No 2011ZX02704, the National Natural Science Foundation of China under Grant No 51205387, and the Science and Technology Commission of Shanghai under Grant Nos 11nm0500300 and 14XD1425300.

Abstract

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.