Effect of mechanical strain on the NBTI of short-channel p-MOSFETS: Role of impactionization

The effect of mechanical strain (MS) and channel length reduction (CLR) on the NBTI of the ultra-thin SiO
2
(28 Å) gate p-MOSFET is investigated. Results show that for effective gate stress voltage |V
g
− V
th
| below the threshold of impact ionization (II), MS and CLR have negligible impact on NBTI. On the other hand, for |V
g
− V
th
| approaching and exceeding the II threshold, stress induced degradation (threshold voltage shift |ΔV
th
|) exhibits increased sensitivity on MS and CLR, i.e. compressive-strained and short-channel devices exhibit a significant increase in |ΔVth|. This new observation is able to resolve conflicting reports regarding the effect of MS and CLR on NBTI.