Effect of Ambient on the Recovery of Hot-Carrier Degraded Devices

nMOSFETs have been degraded by hot-carrier injection and recovered by annealing in various ambients. Hydro-gen will depassivate from the interface due to the hot-carriers, creating dangling bonds, which will cause a shift in the various parameters like the threshold voltage, the subthreshold swing and the interface defect density. This paper investigates how the various ambients (argon, hydrogen, hydrogen plasma and atomic hydrogen) influence the recovery rate of these parameters. Results are discussed in the framework of Stesmans' model for hydrogen passivation at the interface. Furthermore, the influence of a silicon nitride scratch protection layer on the recovery is investigated. These results can be used to enhance the recovery rate and achieve more recovery at a lower anneal temperature, which is important for delaying the accumulative effect of hot-carrier degradation and, as such, extending the device lifetime.