Quantum-mechanical modeling of NBTI in high-k SiGe MOSFETs

Degradation and recovery of a multi-layer high-k SiGe pMOSFET due to the negative bias temperature instability (NBTI) is modeled on the basis of a refined non-radiative multi-phonon (NMP) theory. As the SiGe-layer forms a quantum-well inside the substrate, quantum mechanical effects like subbands are incorporated into the model. In combination with a distribution of defects featuring different energies, barrier heights, and positions inside the oxide, a large range of accelerated stress conditions can be very accurately described. The defects accounting for the recoverable part of the NBTI degradation are finally identified as switching traps.