Strain relaxation mechanism in SiGe-on-insulator fabricated by Ge condensation

Relaxed SiGe-on-Insulator (SGOI) is fabricated using a modified fabrication technique based on Ge condensation by oxidizing the SiGe layer on SOI. In this procedure, the Ge atoms are condensed into the remaining SiGe layer due to the rejection of Ge atoms from the oxide layer and the large diffusion coefficient of Ge in SiGe. Raman measurements reveal that the strain in the SiGe layer is fully relaxed at high oxidation temperature (∼1150°C). Atomic force microscopy (AFM) and transmission electron microscopy (TEM) results indicate that no dislocation is introduced for strain relaxation during the oxidation process. The strain relaxation is explained by a relaxation model involving a compliant substrate, on which the SiGe layer expands laterally via an ultra-low viscosity slippage plane at the SiGe/buried oxide (BOX) interface.