A new off-state drain-bias TDDB lifetime model for DENMOS device

For the first time, a new off-state drain-bias TDDB lifetime model is proposed for DENMOS devices. With the new model, the off-state drain-bias TDDB lifetime can be well predicted from the conventional gate-bias stress without extra long term drain-bias stress. The TDDB lifetime can be decoupled to three components; the small effective stress area and large voltage drop shared by the drain-extension region increase the lifetime, and the band-to-band tunneling current degrades it. The mechanism of oxide breakdown with the off-state drain-bias is also well understood as the oxide traps distributed from the center of channel to the drain side.