Variability model for forming process in oxygen vacancy modulated high-κ based resistive switching memory devices

Forming is one of the key phenomenon that governs the subsequent switchability in high-kappa based resistive random access memory (RRAM) devices. The variability of subsequent switching events (voltage and resistance state), shape and size of filament, reliability of the non-volatile memory device in terms of endurance and retention as well as ultra-low power operation of the memory array all depend on the forming process in one way or the other. As a result, controllability of forming and reduction of the forming voltage is an important design activity in the RRAM technology development process. In this study, we analyze the various factors that affect the forming voltage distribution from a simulation perspective using a Kinetic Monte Carlo (KMC) based formulation of the vacancy defect evolution process in the dielectric. The impact of high-kappa microstructure (grain boundaries), metal-oxide interface roughness, deposition process induced defect distribution as well as role of multi-layer dielectric films on the forming time and spread is investigated in detail. The results of the study provide guidelines for further reliability design initiatives in tightening the forming distribution. (C) 2014 Elsevier Ltd. All rights reserved.