Multilevel data storage using resistive random access memory (RRAM) has attracted significant attention for addressing the challenges associated with the rapid advances in information technologies. However, it is still difficult to secure reliable multilevel resistive switching of RRAM due to the stochastic and multiple formation of conductive filaments (CFs). Herein, we demonstrate that a single CF, derived from selective oxidation by a structured Cu active electrode, can solve the reliability issue. High-quality pyramidal Cu electrodes with a sharp tip are prepared via the template-stripping method. Morphology-dependent surface energy facilitates the oxidation of Cu atoms at the tip rather than in other regions, and the tip-enhanced electric fields can accelerate the transport of the generated Cu ions. As a result, CF growth occurs mainly at the tip of the pyramidal electrode, which is confirmed by high-resolution electron microscopy and elemental analysis. The RRAM exhibits highly uniform and low forming voltages (the average forming voltage and its standard deviation for 20 pyramid-based RRAMs are 0.645 and 0.072 V, respectively). Moreover, all multilevel resistance states for the RRAMs are clearly distinguished and show narrow distributions within 1 order of magnitude, leading to reliable cell-to-cell performance for MLC operation.
Bibliographical noteFunding Information:
We acknowledge the financial support from the R&D Convergence Program of the National Research Council of Science and Technology of Republic of Korea and a Korea Institute of Science and Technology internal project. S.-S.L. appreciates the research grant from the KU-KIST Graduate School. This research was also supported by Hallym University Research Fund, 2017 (Grant HRF-201703-005).
© 2017 American Chemical Society.
- conductive filament
- multilevel resistive memory
- pyramidal electrode
- resistive switching
- surface energy
- tip-enhanced electric field
ASJC Scopus subject areas
- Materials Science(all)