Effect of Electrode Roughness on Electroforming inHfO2and Defect-Induced Moderation of Electric-Field Enhancement

Abstract

The roughness of Pt electrodes is shown to have a direct impact on the electroforming characteristics of Pt=Ti=HfO 2 =Pt device structures. Specifically, an increase in roughness leads to a reduction in the electroforming voltage of HfO 2 , an increase in the failure rate of devices, and a corresponding reduction in resistive switching reliability. A finite-element model is used to investigate the significance of local electricfield enhancement on the breakdown process. This simulation shows that high-aspect-ratio asperities can produce field enhancements of more than an order of magnitude but that the generation and redistribution of defects moderate this effect prior to dielectric breakdown. As a consequence, the effect of field enhancement is less than anticipated from the initial electric-field distribution alone. Finally, it is argued that the increase in the device failure rate with increasing electrode roughness derives partly from an increase in the film defect density and effective device area and that these effects contribute to the reduction in breakdown voltage.

Confining vertical conducting filament for reliable resistive switching by using a Au-probe tip as the top electrode for epitaxial brownmillerite oxide memristive device

“…A finite element method (FEM) was used to map the potential distribution in the device using the COMSOL Multiphysics 5.2 program. We adapted the numerical model approach from previously reported works on RS 18,33 .…”

“…The morphology of the surface and interface can alter the operational characteristics of microelectronic devices significantly. For example, it has been reported that a rough surface morphology can increase the leakage current 17 , reduce breakdown voltage 18 , and reduce the yield in thin film oxide capacitance 19 . However, there are conflicting reports on the effect of surface morphology of the top and bottom electrodes on ReRAM performance.…”

“…In contrast, Sanjoy et al . demonstrated that increasing the roughness of the BE leads to an increase in the failure rate of the device, and consequently, poor switching reliability in the performance of the device 18 . They also observed a wider distribution of switching parameters for the rougher electrode.…”

Understanding the Resistive Switching Phenomena of Stacked Al/Al2O3/Al Thin Films from the Dynamics of Conductive Filaments

“…A simplified model showing the physical mechanisms behind a progressive reduction in SET as well as the surface roughness of the BE is illustrated in Figures 7(a)-7(b). During formation of single/multiple conductive filaments, not only the current compliance but also the surface roughness at the metal/oxide interfaces are important, since this would lead to local electric-field enhancements and then early breakdown [20,21]. Figure 6(b), the power needed to promote continuous resistive switching of that MIM structure is reduced, while the memory window ( ON / OFF ratios) increases.…”

Electrochemical Oxidation Induced Multi-Level Memory in Carbon-Based Resistive Switching Devices

“…This behavior could be attributed to the surface roughness of the OCs (Fig. 2g), which may lead to localized electric-field enhancements leading to an early breakdown 51–53 . A study of the effects of the electrodeposition parameters on the surface roughness 54 , i.e.…”