Strain relaxation in nano-patterned strained-Si /SiGe heterostructure on Insulator

In order to evaluate the strain stability, arrays of strained Si/SiGe nano-stripes and nano-pillars were fabricated by electron-beam lithography (EBL) and reactive-ion etching (RIE). The strain relaxation in the patterned strained Si on SiGe-on-insulator (SGOI) was investigated by high-resolution UV micro-Raman spectroscopy. The Raman measurements before and after patterning indicate that most of the strain in the top strained Si is maintained until scaling down to 300 nm, and relaxation of less than 15% is observed in pillars with a dimension of 150 nm × 150 nm. In the nano-patterned heterostructure strained Si/SiGe, the observed relaxation is small, which is mainly attributed to the fully relaxed and dislocation-free SiGe virtual substrate fabricated by modified Ge condensation.