Fabrication of a strained is on sub-10-nm-thick SiGe-on-insulator virtual substrate

A novel fabrication method for ultra-thin Si1−xGex-on-insulator (SGOI) virtual substrates is proposed for the application of strained silicon-on-insulator (SOI) MOSFETs. Evaluation of the strain in a strained Si layer on this SGOI substrate is also presented. A 9-nm-thick SGOI layer with x=0.56 was formed by dry oxidation of epitaxially grown Si0.9Ge0.1 on a SOI substrate. During the oxidation, Ge atoms were rejected from the surface oxide layer and condensed in the remaining SGOI layer without introducing considerable threading dislocations. After removing the surface oxide layer, a 10-nm-thick Si layer was grown on the SGOI layer. TEM and Raman measurements indicated that the Si layer was pseudomorphically grown on the SGOI layer with 1.0% of tensile strain, corresponding to the strain in a Si layer on fully relaxed Si0.76Ge0.24. This fabrication method is applicable to fully depleted strained SOI MOSFETs with gate lengths of less than 100 nm, which require relaxed and thin SGOI layers (<10 nm) with high x value (x>0.3).