Variability Reduction with Bilayer RRAM Device

• Main Authors: Kempen, Tim, Bende, Ankit, Sarantopoulos, Alexandros, Dittmann, Regina, Bengel, Christopher, Zambanini, Andre, Nielinger, Dennis, Menzel, Stephan, Rana, Vikas
• Format: Conference Proceeding
• Language: English
• Subjects: 3-Bit MLC; Bilayer RRAM; Fluctuations; Hafnium compounds; Memory; Nanoscale devices; Performance evaluation; Resistance; Switches; Variability
• ISSN: 2165-0179
• DOI: 10.1109/CNNA60945.2023.10652783

The inherent stochastic behavior of filamentary switching introduces significant cycle-to-cycle (C2C) fluctuations in the device characteristics, which poses a challenge to the practical applications of resistive random-access memories (RRAMs). Here, we report a simple bilayer oxide-based device structure of \mathbf{TaO}_{\mathbf{x}} /HfO 2 on a 180-nm CMOS substrate to address this variability issue and improve the overall performance of the memory device. The improved switching variability in the bilayer stack is attributed to the incorporation of a conductive \mathbf{TaO}_{\mathbf{x}} thin film, which serves as the switching layer after the conductive filament formation in HfO 2 . More specifically, the switching happens at the interface between the conductive filament and \mathbf{TaO}_{\mathbf{x}} and exhibits a more gradual and less stochastic behavior than filamentary switching. As a result, 3-bit multi-level non-overlapping switching can be demonstrated in \mathbf{TaO}_{\mathbf{x}} /HfO 2 bilayer RRAM devices. These findings could be crucial for the high density data storage applications of RRAMs.