Synaptic Characteristics and Vector-Matrix Multiplication Operation in Highly Uniform and Cost-Effective Four-Layer Vertical RRAM Array

Jihyung Kim, Subaek Lee, Sungjoon Kim, Seyoung Yang, Jung Kyu Lee, Tae Hyeon Kim, Muhammad Ismail, Chandreswar Mahata, Yoon Kim, Woo Young Choi, Sungjun Kim

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

This study implements a highly uniform 3D vertically stack resistive random-access memory (VRRAM) with a four-layer contact hole structure. The fabrication process of a four-layer VRRAM is demonstrated, and its physical and electrical properties are thoroughly examined. X-ray photoelectron spectroscopy and transmission electron microscopy are employed to analyze the chemical distribution and physical structure of the VRRAM device. Multilevel capability, reliable endurance (>104 cycles), and retention (104 s) are successfully obtained. Synaptic memory plasticity, such as spike time-dependent plasticity, spike rate-dependent plasticity, excitatory post-synaptic current, paired-pulse facilitation, and long-term potentiation and depression is presented. Finally, the vector-matrix multiplication (VMM) operation is conducted on a 4 × 12 VRRAM array, according to the low resistance state ratio. It is ascertained that the accuracy drop, which can occur due to VMM error, can be limited to a decrease of less than 0.44% point. Utilizing the high-density, multilevel, and biological characteristics of VRRAM, it is possible to implement high-performance neuromorphic systems that require densely integrated synaptic devices.

Original languageEnglish
Article number2310193
JournalAdvanced Functional Materials
Volume34
Issue number8
DOIs
StatePublished - 19 Feb 2024

Keywords

  • VRRAM
  • neuromorphic system
  • resistive random-access memory
  • synaptic devices
  • vector-matrix multiplication

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