Understanding the switching mechanism in RRAM using in-situ TEM

The understanding of the switching mechanisms in resistive random access memory is of interest as one can use the fundamental mechanisms to better design the memory structure for enhancing both switching and reliability performance. Various analytical methods have been explored to better understand the wear-out and eventual failure mechanisms of RRAM stacks. This includes atomic-scale characterization methods like STM-/AFM-based techniques as well as enhanced TEM techniques and it derivatives like in-situ analysis while stressing the RRAM samples through electrical, optical and mechanical means at evaluated temperature. In this talk, we show that a direct observation of the mechanisms responsible for the switching phenomena in metal/oxide/semiconductor(MIS) RRAM stacks is possible by retrofitting a TEM sample holder with an electrical feed-through to a STM tip that applies an electrical bias to the MIS RRAM stack of interest. Real-time (or in-situ) switching information can be obtained for both SET and RESET cases. The developed techniques have been proven reliable in performing switching cycles many times while observing the switching phenomena under TEM analysis at nano-scale.