Observation of degradation and recovery of stacked HfOx/ZrOy/HfOx MOSFETs

The 28nm hafnium-based gate dielectric with a profile of HfOx/ZrOy/HfOz (HZH) was deposited by atomic layer deposition (ALD) technology. Different nitridation and annealing process conditions on stacked high-k layers were applied to probe the promotion of device performance. One of the effective stress methods to expose the dielectric integrity is the voltage-ramping dielectric breakdown (VRDB). Using this stress method with forward or backward bias, the degradation or recovery efficiency for the tested devices can be exhibited with the performance of stress induced leakage current (SILC), soft breakdown (SBD), progressive breakdown (PBD), and hard breakdown (HBD). The possible degradation and recovery mechanisms are also studied to figure out the relationship of nitridation and annealing impacting the quality of high-k layers.