Lattice relaxation and dislocation generation/annihilation in SiGe-on-insulator layers during Ge condensation process

Dislocation behaviors in SiGe-on-insulator (SGOI) layers during the Ge condensation process are systematically studied by employing transmission electron microscopy, X-ray diffraction, Raman spectroscopy and secondary ion mass spectroscopy, in order to obtain insights into sufficient relaxation of SGOI layers with good crystal quality. It is found that misfit dislocations (MDs) are generated in the ramping up process in Ge condensation, whereas they disappear and threading dislocations (TDs) are generated after the oxidation process. This TD generation is attributable to the fact that the MDs were fragmented into dislocation half-loops and then rose to the SiGe surface. Thus, suppression of the rising motion is a key to fabricating high-quality SGOI substrates by the Ge-condensation technique.