Influence of Nano Abrasive on Chemical Mechanical Ultra-Precision Machining of Sapphire Substrate Surfaces

Abstract

Sapphire (α-Al2O3) single crystal combines many good mechanical and optical properties that make it become the material of choice in a variety of modern Hi-Tech applications The use of CMP technique can produce high quality surface finishes at low cost and with fast material removal rates. In CMP process, nanoabrasive is very important parameters in determining the removal rate. In this paper, the influence mechanism of nanoabrasive on sapphire substrate CMP was analyzed deeply. The main kinetics processing was discussed in detail. According to sapphire substrate properties, alkali slurry was chosen and the mix of SiO2 and Al2O3 sol was selected as nanoabrasive, and the particle size was 20~30nm. The results show that adding nanoalumina with the concentration of 20ml / L in the main abrasive can make the chemical action balance with the mechanical action in the CMP process, so that the substrate removal rate is well improved, and the surface roughness can be reduced to 0.236nm by adjusting the process parameters and slurry ratio. Such data meets the super smooth requirement and the optimal sapphire surface can be gotten. So such slurry with mixed abrasive can be as rough polishing slurry and can improve the polishing efficiency.