Transient to temporarily permanent and permanent hole trapping transformation in the small area SiON P-MOSFET subjected to negative-bias temperature stress

Examining the drain current recovery traces of a small area SiON p-MOSFET subjected to repeated NBTI stress and relaxation cycling reveals direct evidence of transient to permanent hole trapping transformation inferred from previous studies on big area devices. The results show that the emission times of hole traps are not time-invariant (as normally presumed) but can increase due to evolution of the defect sites into more structurally stable forms. In addition, a new type of switching hole traps, exhibiting intermittent charging during stress and occasional increase in emission time by ~5 orders of magnitude, is observed.