Frequency dependent dynamic charge trapping in HfO₂ and threshold voltage instability in MOSFETs

摘要

In this paper, we perform the first investigation of biased threshold voltage instability (BTI) in MOSFETs with MOCVD HfO₂ gate dielectrics under both static and dynamic stress. For an ac stress of a given gate voltage amplitude, we observed reduction of BTI degradation with an increase in stress frequency for both n- and p-MOSFETs. A physical model that accounts for two-step procedure of trap activation (de-activation) and carrier capture (emission) in the HfO₂ dielectric under stress is proposed. Simulation results based on the new model shows good agreement with all experiment data.