Effects of channel orientation, high-k gate stacks and stress on UTB-FETs: a QDD simulation study

In this work we propose a unified model for the low-field effective electron mobility in SOI and DG-MOSFETs with ultrathin SiO2/HfO2 gate stacks, different substrate and channel orientations and uniaxial stress conditions. The model accounts for quantum-confinement effects in the MOSFET channel. Next, we apply this mobility model to a 1D quantum drift-diffusion (QDD) transport model in order to investigate the extent to which the low-field mobility impacts the I-V characteristics. Short (L = 22 nm) DG-FETs, where mobility is affected by quantum-confinement effects, ultrathin SiO2/HfO2 gate stacks and metal gate, have been investigated. Finally, the correlations between the mobility enhancement induced by uniaxial stress in a 22 nm DG-FET, the on-current and transconductance are examined.