Towards understanding recovery of hot-carrier induced degradation

This article treats the recovery of hot-carrier degraded nMOSFETs by annealing in a nitrogen ambient. The recovery rate is investigated as a function of the annealing temperature, where the recovery for increasing temperatures is in agreement with the passivation processes. At the original post-metal anneal temperature of T = 400 °C, the device's original performance is fully restored. Higher temperatures induce a permanent, unrecoverable change to the devices, manifested in a gradual VT shift. The recovery rate is found to be independent of both the transistor gate length and the cooling rate (quench, slow and stepped cooling) upon annealing. These findings are used to gain further understanding of the mechanisms behind the recovery of hot-carrier damage. The recovery rate exhibits Arrhenius behavior and the recovery data are consistent with Stesmans' recovery model.