Evaluation of Anisotropic Biaxial Stress in Si1-X Ge x /Ge Mesa-Structure by Oil-Immersion Raman Spectroscopy

Abstract

Si1-x Ge x is one of the prospective materials for the next-generation transistors due to its high carrier mobility, especially for high Ge concentration Si1-x Ge x . Inducing strain in the Si1-x Ge x leads to transistor performance improvement, however it is difficult to evaluate strain induced in the channel region because the strained Si1-x Ge x channel may be scaled down to nanosize and relaxed complicatedly. We adopted oil-immersion Raman spectroscopy to evaluate the stress in the Si1-x Ge x nanostructure. In this technique, the anisotropic biaxial stress state in the Si1-x Ge x nanostructure can be evaluated. As a result, the nanostructure size dependence of the biaxial stress states in the Si1-x Ge x mesa structure on the Ge substrates was obtained, which was confirmed for the Si1-x Ge x with 76, 85, 92% Ge concentrations.