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

Abstract

In high-κ (HfSiON and HfLaO) metal gate stacks, the traps leading to gate current Ig random telegraph noise (RTN) are found to be effectively passivated by bipolar switching from negative gate bias, where RTN and threshold voltage variation (ΔVT) are reduced significantly or even disappear. The reduction of RTN, ΔVT and Ig 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.