PBTI for N-type tunnel FinFETs

摘要

This paper reports the positive bias temperature instability (PBTI) characteristics for n-type fin-channel tunnel field-effect transistors (TFETs) with high-k gate stacks. The subthreshold slope (SS) is not degraded at all while the threshold voltage (V) shifts in the positive direction by the PBTI stress. The activation energy of ΔV for TFETs is almost the same as FinFETs, indicating that the PBTI mechanism for TFETs is almost the same as FinFETs. It was found that by applying a positive bias to the n-drain, the PBTI lifetime is dramatically improved as compared with that in the conventional stress test. This is because carrier injection from the n-drain is the main cause of the PBTI, especially for n-type TFETs. Thus, to accurately predict the PBTI lifetime of n-type TFETs, it is necessary to apply a drain bias for the reliability test.