A probe of reliability issues of oxide electrolyte based CBRAM

Conductive bridge random access memory is considered to be a promising candidate or complementary component to the traditional charge based memory. In-depth understanding of the failure behavior is essential for performance optimization. In this work, the failure mechanisms of endurance and retention of HfO₂-based cell were studied in a 1 kb array. The degradation of high resistance state was found to exist in the majority cases of endurance failure (stuck at low resistance state). Based on high resolution transmission electron microscopy analysis, the copper accumulation in the filament was found to be the dominant reason behind the endurance failure. The mechanism of retention failure was found related with the lateral diffusion of copper species from the filament to its surrounding (or to the tunneling gap from the filament tip to counter electrode). The retention of high resistance state was degraded with the switching cycle, whereas that of low resistance state was improved. This work provides a basic understanding on the failure mechanism of electrochemical resistive switching memory.