Feasibility of SILC recovery in Sub-10-Å EOT advanced metal Gate-High-κ Stacks

Voltage-induced recovery of dielectric breakdown is a well known phenomenon that has recently been proposed as an effective technique to rejuvenate nanoscale device performance and enhance the reliability lifetime of ultrathin high-κ gate stacks. Considering that most of the circuits at operating conditions take years to suffer soft breakdown (BD) as estimated by extrapolation models, it would be potentially useful to probe whether the pre-BD defect generation-induced time-dependent leakage evolution of the dielectric, commonly referred to as the stress-induced leakage current (SILC), can be reversed permanently so that circuit performance is enhanced from time to time even before the percolation event. In this letter, we investigate the feasibility of SILC recovery in state-of-the-art sub-10-Å equivalent oxide thickness TiN-TaN-HfLaO-SiO_x gate stacks by arresting the degradation of the dielectric using carefully chosen compliance values representative of the pre-BD regime. Our results clearly show the improvement in the saturation drive current and transfer characteristics and reduction in gate leakage and noise spectrum in the SILC stage by initiating a simple negative polarity sweep. Reversibility of SILC is attributed to the backward drift of mobile oxygen ions stored in the oxygen soluble metal gate.