Resistance Drift Model for Conductive-Bridge (CB) RAM by Filament Surface Relaxation

The conductive-bridge random access memory (CBRAM) appears as one of the most promising emerging device due to its remarkable low-power programming, extremely fast switching and scalability. The large resistance window and programmed state controllability may allow for efficient multilevel cell (MLC) operation. However, physical models for CBRAM switching and reliability need to be developed for MLC operation and scaling. This work addresses switching and reliability characteristics of CBRAM. Characterization by two different techniques evidences a size-dependent drift of the resistance of the conductive filament (CF) in the set state. Resistance drift is interpreted in terms of surface relaxation due to charged-defect rearrangement. An analytical model for CBRAM drift is thus developed, allowing for state-dependent drift prediction in CBRAM.