Analysis of Cell Variability Impact on a 3-D Vertical RRAM (VRRAM) Crossbar Array Using a Modified Lumping Method

Sujin Choi, Wookyung Sun, Hyungsoon Shin

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3 Scopus citations


In this paper, the read margin (RM) and write power (WP) of 3-D vertical resistive random access memory (VRRAM) are analyzed by considering the variation in RRAM cell (self-rectifying cell) characteristics. To demonstrate the cell variation effect on a large 3-D VRRAM array, we develop a modified lumping method in HSPICE simulator and show that this method substantially reduces the computation time while maintaining high accuracy. Read and write performances including cell variation are investigated according to various array sizes and RRAM characteristics. A large distribution of cell current reduces the RM but hardly affects the WP. Moreover, in 3-D VRRAM with a small number of wordline (WL) layers, a large on/off ratio (RHRS/RLRS) is advantageous for improving the RM and reducing the variation effect. In contrast, a large on/off ratio has little effect on the RM in 3-D VRRAM with many WL layers. This difference occurs because the increased leakage induced in the half-selected cells mainly affects the RM, and the half-selected cells are located in the selected vertical pillar in 3-D VRRAM.

Original languageEnglish
Article number8540861
Pages (from-to)759-765
Number of pages7
JournalIEEE Transactions on Electron Devices
Issue number1
StatePublished - Jan 2019

Bibliographical note

Funding Information:
Manuscript received September 17, 2018; revised October 18, 2018; accepted October 25, 2018. Date of publication November 20, 2018; date of current version December 24, 2018. This work was supported by the Ministry of Education, Science, and Technology within the National Research Foundation of Korea through the Basic Science Research Program under Grant 2017R1A2B4002540. The review of this paper was arranged by Editor J. Kang. (Corresponding author: Hyungsoon Shin.) The authors are with the Department of Electronic and Electrical Engineering, Ewha Womans University, Seoul 03760, South Korea (e-mail: [email protected]).

Publisher Copyright:
© 1963-2012 IEEE.


  • 3-D vertical resistive random access memory (VRRAM)
  • cell variability
  • crossbar array
  • lumping
  • read margin (RM)
  • write power (WP)


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