Random telegraph noise reduction in metal gate high-κ stacks by bipolar switching and the performance boosting technique

In high-κ (HfSiON and HfLaO) metal gate stacks, the traps leading to gate current I
_g
random telegraph noise (RTN) are found to be effectively passivated by bipolar switching from negative gate bias, where RTN and threshold voltage variation (ΔV
_T
) are reduced significantly or even disappear. The reduction of RTN, ΔV
_T
and I
_g
in degraded gate dielectrics is modeled by oxygen ion drift from the oxygen gettering metal gate electrode to re-passivate the traps upon negative gate bias. A performance boosting technique for transistors during operation is proposed. In this technique, the gate is swept by a small negative voltage to induce a bipolar switching and thus boost up performance after long duration of operation.