Influence of soft breakdown on NMOSFET device characteristics

The degradation of important transistor parameters related to soft breakdown and hard breakdown were studied. Long and short channel transistors were homogeneously stressed at elevated temperature until soft breakdown or hard breakdown occurred. The only noticeable signature of soft breakdown is an increase in off current due to enhanced gate induced drain leakage current. This effect arises if the soft breakdown is located within the gate-to-drain overlap region. Soft breakdown generates a spot or path of negative charges in the oxide and therefore enhances gate induced drain leakage current.