Microsecond transient thermal behavior of HfOx-based resistive random access memory using a micro thermal stage (MTS)

Microsecond transient thermal disturbance (TD) on the conduction and switching of HfO _x -based resistive random access memory (RRAM) is investigated using a micro thermal stage (MTS). Temperature-dependent measurement (298-1134 K) induced from MTS is applied to the RRAM during forming, read, write, and reliability measurements for DC and AC conditions. The temperature of the conductive filament (CF) that was inferred from ex-situ TEM observation of the crystallization is > 850 K in [1]. In this work, the time scale of the temperature-dependent measurement is extended from DC down to ~ 10 μs. The contributions of various mechanisms (drift, Soret and Fick diffusion) of the oxygen ion migration are analyzed using MTS-induced heating. Electric field assisted oxygen ion migration is shown to be the dominant switching mechanism for fast AC switching (pulse width 100 ns with the ambient temperature 298-1047 K). During the fast SET and RESET process (100 ns) at 300-600 K, Soret diffusion (due to the temperature gradient) is stronger and enlarges CF while Fick diffusion (due to the concentration gradient) is not noticeable. Above 400-600 K, Fick force overrides Soret force, driving the resistance to a higher value. A compact model is developed to capture the physics, and TD on the array performance is estimated. In the middle layer (16th) of a 3D array (64 × 64 × 32), 20 % of the cells will be programmed with a resistance shift due to local temperature rise, and as a result 2.2% write failure may occur due to the TD caused by the previous programming cycle.