Hot-Carrier degradation of the Random Telegraph Signal amplitude in submicrometer Si MOSTs

Abstract

This paper studies the Hot-Carrier (HC) degradation of submicrometer Si MOSTs by the changes in the Random Telegraph Signal (RTS) parameters. It is demonstrated that the amplitude of a pre-existing RTS is markedly changed after stress. In linear operation, a reduction is generally observed for n-MOSTs, while an increase is found for p-MOSTs. For larger drain voltages, the changes are most pronounced in reverse operation, i.e. with source and drain switched, for a forward stress. Hence, the trap-amplitude asymmetry increases after stress. As is demonstrated, there exists a close correlation between the observed changes in the RTS amplitude and in the static device parameters. A simple, first-order model is derived, showing that the HC stress-induced reduction (n-channel), or increase (p-channel) is proportional to the variation of the oxide/interface charge density near the drain. Alternatively, it is demonstrated that the normalized change in the RTS amplitude is equal to the normalized conductance change of the narrow hot-carrier damaged region.