Self-Heating During submicrosecond Current Transients in Pr0.7Ca0.3MnO3-Based RRAM

Abstract

In filamentary RRAM, the role of self-heating in set/reset (by ion transport) is well established. However, in nonfilamentary Pr0.7Ca0.3MnO3 (PCMO) RRAM, self-heating during set/reset has not been explored. Recently, we have shown self-heating to explain nonlinearity in dc IV characteristics. In this paper, we present the observation of self-heating using transient current during pulses. We show that the cooling timescale is limited by measurement system timescale (~30 ns). The self-heating-based experimental current transient timescale is longer (50–100 ns) and is not described by simple exponential decay. To explain this behavior, self-heating in PCMO RRAM (where Joule heating and current increase create a positive feedback) is implemented into technology computer aided design simulations. Simulations produce excellent agreement with experiments. Eventually, simulations deviate from experiments when thermally assisted ionic transport during set/reset is not included in the model. To interrupt the continuous self-heating, an n-pulse-train with cooling time between pulses versus single pulse-based set/reset experiment was designed with the same peak bias time. Set/reset effectiveness degrades as n increases while effect of increasing cooling time confirmed a cooling timescale of ~30 ns. Overall, self-heating provides a consistent explanation of the transient currents. Thus, this paper establishes that self-heating considerations must be included for PCMO-based RRAM modeling and design.