Impact of nitrogen in HfON gate dielectric with metal gate on electrical characteristics, with particular attention to threshold voltage instability

Abstract

The impact of nitrogen (N) in HfON gate dielectric on electrical characteristics, particularly on charge trapping induced threshold voltage (Vth) instability, has been investigated in n-channel metal-oxide-semiconductor field effect transistor with TaN metal gate. Compared to HfO2, the enhanced gate capacitance, slightly increased gate leakage current, and degraded interface properties were observed in the HfON gate dielectric. The incorporation of N into HfO2 also caused mobility degradation at low effective field region. Moreover, charge trapping induced Vth instability was found to be severer in HfON than in HfO2, which could be attributed to increased bulk traps induced by the incorporated N.