The Failure Mechanism of Drain Bias TDDB and Characterization of Lifetime Model for HV Depmos

Abstract

The failure mechanism of drain bias TDDB for HV De-PMOS was studied, which is induced by minority, electrons for PMOS, from ion impact ionization at high V d injection to drift region dielectrics. Multistage Ig-t curve behavior was observed during off-sate drain bias TDDB test, electrons injected into drift region (Ig increase) at initial stage, electrons trapped in drift region dielectrics (Ig decrease) at 2nd stage and percolation path formed (gate oxide breakdown) at last stage. Furthermore, power law model, used to extrapolated drain bias TDDB lifetime, and its characteristics, n value, Ea, width factor were studied. Finally, through quick method to screen effective result from various optimized process experiments, drain bias TDDB lifetime was significantly improved.