Impact of La on the bias-temperature instability of the HfSiO High-κ n-MOSFET

Lanthanum (La), which has been used in recent works to tune the threshold voltage of HfSiO high-κ n-MOSFETs, is shown to introduce a new bulk degradation mechanism. Unlike the conventional charge trapping mechanism which exhibits low activation energy (∼0.05 eV) and fast post-stress recovery, the La induced degradation mechanism is found to be relatively permanent and has higher activation energy (∼0.26 eV). The latter is expected to have a significant impact on the positive-bias temperature instability of n-MOSFETs employing La-doped high-κ gate dielectrics.