Multi-Level RTN with Certain Regularities in Oxide-RRAM: Experiments, Defect Dynamics and 3D Multi-Physics Modeling

The random telegraph noise (RTN) of oxide-based resistive random-access memory (RRAM) represents rich underlying physics and defect dynamics. This paper investigated the multi-level RTN phenomena with certain regularities in the Ti/HfOx/TiN RRAM. The investigation is based on the comprehensive measurements and careful modeling of the multi-phonon trap-assisted tunneling (MPTAT) through a developed RRAM simulator, assisted by First-Principle calculations of oxygen vacancy (Vo) states. It is found that the participation of the polaron band of Vo is the main reason to produce the RTN of RRAM, and the observed two-level RTN is attributed to the transition of Vo between V0 and V1-, and can be utilized to locate defects. The multi-level RTN arises from the collective action of Vo at different positions in the conductive filament (CF) gap, which can distinctly affect the current fluctuation ($\Delta\mathrm{I}$), capture time (τc), and emission time (τe),