Scaled X-bar TiN/HfO2/TiN RRAM cells processed with optimized plasma enhanced atomic layer deposition (PEALD) for TiN electrode

We proposed a new, simpler, and fully BEOL CMOS-compatible TiN/HfO2/TiN RRAM stack using the Plasma Enhanced Atomic Layer Deposition (PEALD) for the top-electrode TiN processing, demonstrating attractive bipolar switching properties (by positive RESET voltage to the PEALD TiN) in a functional size down to 2275 nm2 (35 nm × 65 nm). Stable switching was observed between a High-Resistive State HRS (∼1 MΩ) and a Low-Resistive State LRS (∼100 kΩ), using a low program current of ∼1 μA. Two different LRS states can be obtained depending on the current compliance (CC) during SET switching, either 100 μA (high-CC LRS) or 10 μA (low-CC LRS), resulting, respectively in LRS resistances of 10 kΩ or 100 kΩ. The projected retention stability of low-CC LRS is ⩾10 years at 80 °C, which is the retention minimum of the TiN/HfO2/TiN RRAM stack. The temperature-dependent resistance showed a non-metallic behavior for the low-CC LRS state (∼100 kΩ), suggesting gentle filament formation.