Significant Enhancement of HCD and TDDB in CMOS FETs by Mechanical Stress

Significant enhancement of hot-carrier degradation and time-dependent dielectric breakdown by mechanical stress was observed in CMOS FETs. Mechanical stress was induced locally in the channels of p- and n-type FETs by applying a vertical load with a diamond tip of a nanoindenter. The induced GPa level stress was calculated with finite element modeling. Mechanical stress induces a piezoresistance effect in both p- and n- channels, leading to an increase in source/drain leakage and drive currents and drastic enhancement of impact ionization. This in turn results in strongly enhanced hot-carrier degradation and hot-electron-induced punch-through effects in pFETs and enhanced hot-carrier degradation and time-dependent dielectric breakdown in nFETs.