Relaxed silicon–germanium-on-insulator fabricated by oxygen implantation and oxidation-enhanced annealing

The application of separation-by-implantation-of-oxygen (SIMOX) for silicon-germanium-on-insulator (SGOI) fabrication is always limited by the Ge loss caused by the high temperature annealing. A unique SIMOX method was introduced to fabricate SGOI and resolve the problem of Ge loss. During the process, a SiO2 layer was formed pre-annealing to block the Ge out-diffusion. As the x-ray rocking curve and Raman spectra studies show, the Ge fraction of the SGOI was improved to 17 at.%. The final sample exhibits a planar and continuous buried oxide layer, sharp interfaces and a defect free top SiGe layer as the cross-sectional transmission-electron-microscopy (XTEM) and secondary-ion-mass-spectrometry studies show. The Rutherford backscattering spectroscopy demonstrated that the superficial SiGe layer was superior in quality (derived channelling yield of 10%). The results indicate that the additional step of thermal oxidation pre-annealing is vital to resolve the problem of Ge loss and the modified SIMOX process is applicable for SGOI fabrication.