The physical origins of fast and slow components in NBTI degradation for p-MOS transistors with SiON gate dielectric

Abstract

In this paper, we summarize our recent systematic investigation and our view on the fast and slow components of Negative Bias Temperature Instability (NBTI) degradation in p-MOSFETs with ultra-thin SiON gate dielectric. (1)For the slow NBTI component measured by the conventional DC method, we show evidence that the degradation and recovery is due to interface trap Nit generation and passivation. A recent debate regarding the physical origin in recovery phase is clarified. Nit measured by conventional CP and DCIV methods is underestimated due to passivation under measurement; (2) Due to the degradation during initial threshold voltage measurement, the existing (slow) on-the-fly measurement distorts (overestimates) the slope and induces a kink at early stress time in the Log-Log curve of static NBTI degradation time evolution. A fast on-the-fly method is developed to overcome this problem. (3) An ultra-fast (100ns) transient pulse Vth measurement method is developed to avoid the recovery of fast NBTI component during measurement, and is compared to the fast on-the-fly measurement results with excellent agreement. (4)Our experimental results and analysis show that there are two NBTI components, fast and slow, with different physical origins. The fast component measured by ultra-fast pulsed method is mainly due to trapping de-trapping of oxide charge. All experimental results can be well explained in this scheme with very good quantitative agreement between the modeling and the experimental data. © The Electrochemical Society.