Development of binder-free CMG abrasive pellet and finishing performance on mono-crystal sapphire

Chemo-mechanical-grinding (CMG) is a fixed abrasive process by integrating chemical reaction and mechanical grinding for sapphire wafer finishing, and shows advantages in surface integrity, geometric controllability and waste disposal. However, the material removal rate (MRR) obtained by the traditional CMG wheel is not high enough to meet the requirement from the mass production of sapphire wafers. As a potential solution, a new CMG wheel with extremely high abrasive concentration has been proposed. This paper targets on developing of binder-free abrasive pellets (BAP) with 100 wt% abrasive as well as investigating the performance of BAP in sapphire wafer finishing. The results of CMG experiment reveal that the MRR and surface roughness (Ra) of sapphire wafer finished by BAP constructed CMG wheel are able to reach 1.311 μm/h and 0.993 nm respectively. The characterization by Raman microscope indicates that the finished sapphire wafer also owns excellent subsurface integrity.