New insight on negative bias temperature instability degradation with drain bias of 28 nm High-K Metal Gate p-MOSFET devices

Abstract

The degradation of negative bias temperature instability (NBTI) on 28nm High-K Metal Gate (HKMG) p-MOSFET devices under non-uniform stress condition has been systematically studied. We found the asymmetry between forward and reverse Idsat shift under non-uniform stress condition is significant for long channel devices even under low drain bias stress (e.g., Vds=−0.1V and gate channel length L=1μm), and seems to be dominated by a minimally required critical length (L=0.2μm derived from the experimental data). To the authors’ best knowledge, these are new phenomena reported. We attribute these anomalous NBTI characteristics with drain bias to the local self-heating (LSH) activated NBTI degradation mechanism. One semi-empirical analytical model, which fits well with our experimental data, is then proposed in this paper.