Computational model for predicting structural stability and stress transfer of a new SiGe stressor technique for NMOS devices

Abstract

A new method to induce tensile stress in a PDSOI NMOS device for RF applications is proposed, which is based on relaxing a SiGe layer built underneath silicon. By means of TCAD simulations, we demonstrate that stress transfer from SiGe to Si occurs by means of at least two different mechanisms: SiGe relaxation due to amorphization and the formation of Stacking Faults during recrystallization. By considering both phenomena, a tensile stress of 0.5 GPa can be injected into the silicon channel. Moreover, the impact of annealing steps on the detrimental out-of-SiGe Ge diffusion has been simulated by considering an inter-diffusion model, showing the importance of adapting the PDSOI process flow to account for the presence of the new stressor.