Self-consistent physical modeling of SiOx-based RRAM structures

Abstract

Abstract-We apply a unique three-dimensional (3D) physics-based atomistic simulator to study silicon-rich (SiOx, x<2) resistive switching nonvolatile memory (RRAM) devices. We couple self-consistently a simulation of ion and electron transport to the 'atomistic' simulator GARAND and a selfheating model to explore the switching processes in these structures. The simulation model is more advanced than other available phenomenological models based on the resistor breaker network. The simulator is calibrated with experimental data, and reconstructs accurately the formation and rupture of the conductive filament in the 3D space. We demonstrate how the simulator is useful for exploring the little-known physics of these promising devices, and show that switching is an intrinsic property of the SiOx layer. In general, the simulation framework is useful for providing efficient designs, in terms of performance, variability and reliability, for memory devices and circuits. The simulator validity is not limited to SiOx-based devices, and can be used to study other promising RRAM systems based, e.g., on transition metal oxides.

Advanced physical modeling of SiO<inf>x</inf> resistive random access memories

“…3. Two important aspects of the simulator need to be highlighted: (i) using a fundamental understanding of vacancy generation to extract important parameters such as activation energies and diffusion barriers (not used in our previous work [9], [10]), and (ii) integrating an advanced structure generator into the simulation framework, which allows the generation of a simulation structure of any arbitrary geometry and material profile. The structure editor is particularly useful when studying realistic SiO x RRAM structures incorporating siliconrich areas (defect rich areas or areas with Si nano-inclusions [2]) in the oxide, as is the case here.…”

The mechanism underlying silicon oxide based resistive random-access memory (ReRAM)

“…To elucidate the mechanism of the ReRAM already a variety of models were proposed such as formation and devastation of conducting filaments, based on Joule heating effect, trapping and detrapping of charge carriers, electrochemical migration of oxygen ions and vacancies, Schottky barrier behaviour at the interface, unified physical model, thermal dissolution, filament anodization model, thermo chemical reaction, conformational change (organic materials) and sp 2 /sp 3 conversion (amorphous carbon and others) [13][14][15][16][17][18][19][20]. In which, conducting filament explains the low resistance state (LRS) and high resistance state (HRS) by the creation and rupture of CF [21]. Unfortunately, the fluke nature of filamentary switching mechanism at atom scale greatly hinder the future development of this technology and the assessment of performance via experimentation [22].…”