Probing the strain states in nanopatterned strained SOI

Using strained SOI as a strategy to enhance the performance of Si-based electronic devices raises fundamental questions about the stability of the strain during different processing steps. In this work, we elucidate the influence of nanoscale pattering, a crucial step in device fabrication, on the strain states. UV micro-Raman and high resolution transmission electron microscopy were employed to quantify the strain in the strained layers. Post-patterning strain in different nanostructures was evaluated by UV micro-Raman. Our data demonstrate that the formation of free surfaces upon pattering leads to a partial relaxation of the strain. The extent of the relaxation was found to depend on the lateral dimension and the geometry. A detailed mechanistic picture is presented based on 3D finite element simulations.