Flexible 3D memristor array for binary storage and multi‐states neuromorphic computing applications

• Published in: InfoMat Vol. 3; no. 2; pp. 212 - 221
• Main Authors: Wang, Tian‐Yu, Meng, Jia‐Lin, Chen, Lin, Zhu, Hao, Sun, Qing‐Qing, Ding, Shi‐Jin, Bao, Wen‐Zhong, Zhang, David Wei
• Format: Journal Article
• Language: English
• Published: Melbourne John Wiley & Sons, Inc 01.02.2021; Wiley
• Subjects: 3D crossbar; brain‐inspired computing; flexible memory; low‐temperature ALD; multilevel storage
• DOI: 10.1002/inf2.12158
• ISSN: 2567-3165

The demand of flexible neuromorphic computing electronics is increasing with the rapid development of wearable artificial intelligent devices. The flexible resistive random‐access memory (RRAM) is one excellent candidate of high‐density storage devices. However, due to the limitations of fabrication process, materials system and device structure, it is difficult to prepare flexible 3D high‐density network for neuromorphic computing. In this paper, a 3D flexible memristors network is developed via low‐temperature atomic layer deposition (ALD) at 130°C, with potential of extending to various flexible electronics. The typical bipolar switching characteristics are verified in RRAM units of 3D network, including first, second and third layers. Besides binary storage, the multibit storage in single unit is demonstrated and the storage density is further increased. As a connection link between binary storage and brain‐inspired neuromorphic computing, the multibit storage capability paves the way for the tunable synaptic plasticity, for example, long‐term potentiation/depression (LTP/LTD). The 3D memristors network successfully mimicked the typical neuromorphic functionality and realized ultra‐multi conductance states modulation under 600 spikes. The robust mechanical flexibility is further demonstrated via LTP/LTD emulation under bending states (radius = 10 mm). The 3D flexible memristors network shows significant potential of applications in high‐performance, high‐density and reliable wearable neuromorphic computing system. The 3D flexible memristors array consists of three‐layer crossbar structure, where the resistive random‐access memory (RRAM) of first, second and third layers correspond to top, middle and bottom units, respectively. The single unit in every cross point is a metal‐insulator‐metal (MIM) based RRAM and the final 3D structure is formed by stacking the crossbar structure on the flexible substrate. With the compliance current of 400 μA, first, second and third‐layer units all exhibit typical bipolar resistive switching curves, indicating the high‐density storage capability of the 3D memristors array via 3D structure design.