The crystallographic change in sub-surface layer of the silicon single crystal polished by chemical mechanical polishing

The effect of the contact nominal pressure on the surface roughness and sub-surface deformation in chemical mechanical polishing (CMP) process has been investigated. The experimental results show that a better surface quality can be obtained at the lower pressure, and the thickness of sub-surface deformation layer increases with the increase of the pressure. In CMP process, polishing not only introduces amorphous transformation but also brings a silicon oxide layer with a thickness of 2–3 nm on the top surface. The atomic structure of the material inside the damage layer changes with the normal pressure. Under a higher pressure (125 kPa), there are a few crystal grain packets surrounded by the amorphous region in which the lattice is distorted, and a narrow heavy amorphous deformation band appears on the deformation region side of the interface. Under a lower pressure, however, an amorphous layer can only be observed.