Abstract: Abstract： In order to reveal the mechanism of tribochemical polishing process between sapphire wafer and silica colloid particles, contact conditions were discussed by using the tribochemistry theory and nanoindentation method. Stress distribution of sapphire wafer under unload condition was simulated by using the finite element method. When the contact stress along the subsurface of sapphire wafer is about 5 to 15 GPa, the activation energy during tribochemical reaction is approximately 14.46 kJ/mol, and 0.07 to 0.23 μm/min for the reaction rate. When the contact radius between silica colloid and sapphire wafer is around 15 to 21 nm during the tribochemistry reaction process, the deformation value is about 6.88 to 10.22 nm. The experimental results for lowloading nanoindentation and polishing process show that when the contact force is less than 0.7 mN, without considering the hardness and form errors between diamond indent tip and abrasive grit, the polished sapphire wafer can achieve a smooth surface with Rt 38.19 nm and Ra 3.62 nm.

Key words: Key words： sapphire wafer, tribochemical polishing, nanoindentation, finite element method； nanoindentation method