The effect of externally imposed mechanical stress on thehot-carrier-induced degradation of deep-sub micron nMOSFET's

The influence of externally imposed mechanical stress (MS) on the hot-carrier-induced degradation of MOSFET's is studied. For nMOSFET's, tensile (compressive) stress increases (decreases) degradation. This effect is ascribed to the piezoresistance effect which causes a change of the hot-carrier generation. It is demonstrated that, in contradiction with earlier reports in literature, externally imposed mechanical stress has no influence on carrier trapping, nor on interface trap creation. Also, since the piezoresistance coefficient is reduced in deep-sub micron transistors, the effect of mechanical stress on hot-carrier degradation becomes negligible for 0.35-μm transistors