Self-Selection RRAM Cell With Sub- $\mu \text{A}$ Switching Current and Robust Reliability Fabricated by High- $K$ /Metal Gate CMOS Compatible Technology

A high-K/metal gate (HKMG)-stack (TiN/Al-doped-HfO x /SiO 2 /Si)-based bipolar resistive random access memory (RRAM) cell is proposed and fabricated by 28/20-nm HKMG CMOS compatible technology. Robust reliability behaviors (retention at $200~ {^{\circ }}\text {C} > 4 \times 10^{4}$ s and endurance $> 10^{{{5^{\vphantom {\frac {}{,}}}}}}$ cycles) and ultralow switching current ( $ for RESET and $ for SET) are both demonstrated. The sub- $\mu \text{A}$ switching current and self-selection nonlinear $I$ – $V$ characteristics are attributed to the SiO 2 interfacial layer rather than the decrease of conductive filament size and oxygen vacancy ( $V_{O}$ ) density, which can be verified by HRTEM and measured conduction behavior. Therefore, robust reliability property is also achieved. The demonstrated excellent memory characteristics of HKMG stacked RRAM cell enable constituting 1-Mb workable crosspoint array even though the feature size scales down to 10 nm according to the HSPICE simulation.