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Requirement of New Memory for Improving Computing Performance in Von-Neumann Architecture

  • Latency gap between DRAM and FLASH memory.
  • Requirements of SCM: Non-volatility, fast speed, low cost per bit and high density.
  • RRAM is one of the most promising memories for SCM thanks to its various advantages.
Resistive Random Access Memory (RRAM)

  • Metal-insulator-metal (MIM) structure
  • External bias changes resistance states (LRS or HRS states) of the insulating layer.
  • Advantages of RRAM: Simple structure, excellent scalability, high speed, low power, long endurance and CMOS compatibility.
Types of Resistive Random Access Memory (RRAM)

  • Filament Type: If conduction path is determined by filaments, formed by gathering of ions moved by external bias.
    • Valence Change Memory (VCM): filament based on oxygen vacancy ▶ Relatively good retention
    • Electrochemical Metallization Memory (ECM): filament based on metal ions ▶ Extremely high HRS resistance
  • Non-filament Type: If conduction path is not confined to filaments consisting of ions.
    • Interface type RRAM: Interface barrier modulated by oxygen ions movement ▶ Excellent uniformity

  1. 1.   J. Woo et al., "Optimized Programming Scheme Enabling Linear Potentiation in Filamentary HfO2 RRAM Synapse for Neuromorphic Systems." IEEE Transactions on Electron Devices 63.12 (2016): 5064-5067.
  2. 2.   B. Attarimashalkoubeh et al., "Effects of Ti buffer layer on retention and electrical characteristics of Cu-based conductive-bridge random access memory (CBRAM)." ECS Solid State Letters 3.10 (2014): P120-P122.
  3. 3.   K. Moon et al., "High density neuromorphic system with Mo/Pr0.7Ca0.3MnO3 synapse and NbO2 IMT oscillator neuron." 2015 IEEE International Electron Devices Meeting (IEDM). IEEE, 2015.