Strain Engineering for Germanium-on-Insulator Mobility Enhancement with Phase Change Liner Stressors

We investigate the strain in various Ge-on-insulator (GeOI) micro-structures induced by three phase-change materials (PCMs) (Ge2Sb2Te5, Sb2Te3, GeTe) deposited. The PCMs could change the phase from amorphous state to polycrystalline state with a low temperature thermal annealing, resulting in an intrinsic contraction in the PCM films. Raman spectroscopy analysis is performed to compare the strain induced in the GeOI microstructures by various PCMs. By comparison, Sb2Te3 could induce the largest amount of tensile strain in the GeOI micro-structures after the low temperature annealing. Based on the strain calculated from the Raman peak shifts, finite element numerical simulation is performed to calculate the strain-induced electron mobility enhancement for Ge n-MOSFETs with PCM liner stressors. With the adoption of Sb2Te3 liner stressor, 22% electron mobility enhancement at N-inv = 1x10(13) cm(-2) could be achieved, suggesting that PCM especially Sb2Te3 liner stressor is a promising technique for the performance enhancement of Ge MOSFETs.