Dielectric Breakdown In Ultra-thin Hf Based Gate Stacks: A Resistive Switching Phenomenon

摘要

The gate dielectric breakdown (BD) reversibility in MOSFETs with ultra-thin hafnium based high-k dielectric is studied. The phenomenology is analyzed in detail and the similarities with the resistive switching phenomenon emphasized. The results show that after BD, the switch between two different conductive states in the dielectric is possible. We have demonstrated that the conduction in both states is local, which has been verified through CAFM measurements. Additionally, the injected charge to the first recovery (Q_R) has been proposed as a parameter to describe the BD reversibility phenomenon. The BD recovery partially restores not only the current through the gate, but also the MOSFET channel related characteristics. The electrical performance of MOSFETs after the dielectric recovery has been modeled and introduced in a circuit simulator. The simulation of several digital circuits shows that their functionality, though somehow affected, can be restored after BD recovery.