Relaxation Effect in RRAM Arrays: Demonstration and Characteristics

In this letter, two distinct retention degradation regions, a rapid resistance relaxation effect followed by a slow resistance loss process, were observed from high-resistance state (HRS) of HfO
_x
-based resistive random access memory (RRAM) array retention tests. The influence of resistance, thickness of HfO
_x
, baking temperature, and RESET pulsewidth on the relaxation effect for HRS were studied in detail. Random telegraph noise (RTN) characterization suggests that this early loss of data for HRS is due to new oxygen vacancies generation which could shorten the gap between the filament and the TaO
_x
layer. Possible causes were provided to describe the relaxation effect and to understand the RTN characteristics correlated with relaxation effect in RRAM array.