THE EFFECT OF EXTERNALLY IMPOSED MECHANICAL-STRESS ON THE HOT-CARRIER-INDUCED DEGRADATION OF DEEP-SUB MICRON NMOSFETS

The influence of externally imposed mechanical stress (MS) on the hot- carrier-induced degradation of MOSFET's is studied, For nMOSFET's, ten sile (compressive) stress increases (decreases) degradation, This effe ct 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 stre ss has no influence on carrier trapping, nor on interface trap creatio n, Also, since the piezoresistance coefficient is reduced in deep-sub micron transistors, the effect of mechanical stress on hot-carrier deg radation becomes negligible for 0.35-mu m transistors.