Using Piezoresistance Model With C- R Conversion for Modeling of Strain-Induced Mobility

The piezoresistance model has commonly been used to describe mobility enhancement for low levels of process induced strain in CMOS technology. However, many reports show it failing to describe the superlinear behavior observed at high levels of stress. This is because the approximation made is only valid for very low stress levels. In this letter, a conversion between the change in conductivity and resistivity is developed such that a piezoresistance model can be applied correctly to calculate the strain-induced mobility changes. Hence, the overall accuracy is improved compared to the conventional formulation. Its significance is confirmed with the results from Monte Carlo simulations of mobility, nMOSFETs, pMOSFETs, and nanowires.