Evaluation of surface microroughness for surface activated bonding

In Surface Activated Bonding (SAB), high surface flatness is required for the stability of bonding. Though RMS (Root Mean Square) is often used for the evaluation of surface roughness, RMS is not always enough to express surface roughness appropriately. Therefore, we introduced a numerical method called as Power Spectral Density function to the surfaces of bonding targets. In this research silicon, gold and copper samples are evaluated.