X-RAY-SCATTERING FROM A ROUGH-SURFACE AND DAMAGED LAYER OF POLISHED WAFERS

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-s urface damage of mechanochemically polished wafers. By fitting the mea sured crystal truncation rod curves it has been shown that polished wa fers are divided into three parts -irregular steps on the surface, a d amaged thin layer beneath the surface and a perfect bulk. The results show that the root mean square of the surface roughness of mechanochem ically polished Fe-doped and/or S-doped InP wafers is one to two atom layers, and that the lateral correlation length of the surface roughne ss is about 3000-7500 Angstrom. The thickness of the damaged region is found to be about 1000 atom layers.