MRS Meetings and Events


EQ11.03.03 2022 MRS Spring Meeting

Controlling the Oxygen Ion Motion Using a Diffusion Barrier Layer in HfOx-Based Analog Memory

When and Where

May 10, 2022
9:15am - 9:30am

Hawai'i Convention Center, Level 3, 318A



Fabia Farlin Athena1,Matthew West1,Qi Jiang1,Wolfgang Buchmaier1,Jinho Hah1,Robert Montgomery1,Riley Hanus1,Samuel Graham1,Eric Vogel1

Georgia Institute of Technology1


Fabia Farlin Athena1,Matthew West1,Qi Jiang1,Wolfgang Buchmaier1,Jinho Hah1,Robert Montgomery1,Riley Hanus1,Samuel Graham1,Eric Vogel1

Georgia Institute of Technology1
Oxide-based non-volatile memory devices such as Resistive Random Access Memory (RRAM) have broad applications, particularly in the field of analog neuromorphic computing<sub>.</sub><sup>1</sup> Analog computing requires a linear change in resistance as a function of applied pulses. Resistance change involves the motion of oxygen ions across a conductive filament in filamentary oxide-based memory. However, if the oxygen ion motion is too abrupt with an applied pulse, the resistance change becomes non-linear, degrading the neuromorphic performance.<sup>2</sup> A diffusion barrier layer with higher activation energy for oxygen ion motion (E<sub>A,O</sub>) can be used at the interface (where the filament is expected to reform during the set) to improve the linearity. A previous study showed that HfO<sub>x</sub> RRAM with an AlO<sub>x</sub> barrier exhibited analog set behavior with an <b>on/off ratio of ~3</b>.<sup>3 </sup>However, SiO<sub>x</sub> has a higher diffusion barrier for oxygen ion motion as compared to AlO<sub>x</sub>.<br/>In this study, the effect of two different barrier layers, AlO<sub>x</sub> (E<sub>A,O</sub>= 1.3 eV) and SiO<sub>x</sub> (E<sub>A,O</sub>= 2.7 eV), on the RRAM switching characteristics and analog temporal responses (e.g., long-term-potentiation and depression, spike-time-dependent-plasticity) of HfO<sub>x</sub> based filamentary memory are explored. A thin ~0.8 nm barrier layer was deposited at the HfO<sub>x</sub>/BE interface via atomic layer deposition (ALD), followed by a ~4.2 nm HfO<sub>x</sub> active layer. A detailed X-ray photoelectron spectroscopy (XPS) depth profile analysis was performed to characterize the composition of the stack. Electrical characterization shows that devices with an AlO<sub>x</sub> barrier layer have a comparable forming voltage (~3.1 V) and set-reset behavior than the HfO<sub>x</sub> device without a barrier layer. However, the devices with a SiO<sub>x</sub> barrier layer show a higher forming voltage (~4.5 V) and an <b>on/off ratio of ~5</b>. The SiO<sub>x </sub>barrier layer devices demonstrate a <b>more</b> <b>gradual set</b>, <b>improved linearity</b> in the potentiation, and significantly <b>less spike-to-spike variation</b> during the analog pulsing compared to HfO<sub>x</sub>/AlO<sub>x</sub> and HfO<sub>x </sub>devices. A COMSOL Multiphysics<sup>®</sup> model is used to develop a fundamental understanding of the observed results. Overall, the experimental results demonstrate that reducing the oxygen ion motion using a SiO<sub>x </sub>diffusion barrier layer at the bottom electrode interface improves the linearity in the analog potentiation of HfO<sub>x</sub>-based memory for neuromorphic applications.<br/>1. J. J. Yang, et al., Nature nanotechnology <b>8</b> (1), 13-24 (2013).<br/>2. K. Moon, et al., Faraday discussions <b>213</b>, 421-451 (2019).<br/>3. J. Woo, et al., IEEE Electron Device Lett. <b>37</b> (8), 994-997 (2016).<br/><b>Acknowledgments: </b>This work was supported by the AFOSR MURI under Award No. FA9550-18-1-0024. In part at the Georgia Tech Institute for Electronics and Nanotechnology, a member of the NNCI, which is supported by the NSF (ECCS-2025462). This material is based upon the work supported by the NSF GRFP under Grant No. DGE-1650044.

Symposium Organizers

Yoeri van de Burgt, Technische Universiteit Eindhoven
Yiyang Li, University of Michigan
Francesca Santoro, Forschungszentrum Jülich/RWTH Aachen University
Ilia Valov, Research Center Juelich

Symposium Support

Nextron Corporation

Publishing Alliance

MRS publishes with Springer Nature