Atomistic simulations of failure mechanisms in ultrascaled HfO_x RRAM arrays

Filamentary Resistive Random Access Memory (RRAM) devices have so far been scaled down to a 2.1 nm [1] feature size, 2 nm thickness [2], and integrated with advanced transistor nodes for active cell selection [5]. Evaluating their ultimate integration density now involves understanding the scales at which switching can be reliably achieved in matrix-like structures, and the associated failure mechanisms. Previous theoretical studies explored ultrascaled RRAM based on static electronic properties and fixed filament geometry [2], or continuum/regular domains [4, 6]. While useful, these approaches do not simultaneously capture the underlying structural irregularity of the switching material, and the finite size/number of atoms involved in the switching process, both of which heavily influence the kinetics of atomic relocation and the resulting current flow [3]. Here we leverage a custom atomistic simulation tool designed to capture such effects to investigate the failure mechanisms which emerge in high-density passive RRAM arrays, as well as insight on how they can be mitigated.