X-ray scattering from a rough surface and damaged layer of polished wafer

Theoretical and experimental investigations were performed to show the application of X-ray crystal truncation rod scattering combined with X-ray reflectivity in the measurements of surface roughness and near-surface damage of mechanochemically polished wafers. By fitting the measured crystal truncation rod curves it has been shown that polished wafers are divided into three parts-irregular steps on the surface, a damaged thin layer beneath the surface and a perfect bulk. The results show that the root mean square of the surface roughness of mechanochemically polished Fe-doped and/or S-doped InP wafers is one to two atom layers, and that the lateral correlation length of the surface roughness is about 3000-7500 AA. The thickness of the damaged region is found to be about 1000 atom layers.