Mobility Modeling in Advanced MOSFETs with Ultra-Thin Silicon Body under Stress

Mobility in advanced MOSFETs with strained ultra-thin silicon body is investigated. We use a two-band k·p model to describe the subband structure in strained silicon thin films. The model provides the dependence of the conductivity effective mass on strain and film thickness. The conductivity mass decreases along tensile stess in [110] direction applied to a (001) silicon film. This conductivity mass decrease ensures the mobility enhancement in MOSFETs even with extremely thin silicon films. The two-band k·p model also describes the non-parabolicity dependence on film thickness and on strain. Dependence of the non-parabolicity parameter on both film thickness and strain reduces the mobility enhancement due to the conductivity mass modification, especially at higher strain values.