Self-selection RRAM cell with Sub-μA 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/SiO₂/Si) based bipolar RRAM cell is proposed and fabricated by 28/20nm HKMG CMOS compatible technology. Robust reliability behaviors (retention @200 °C >4×10⁴ s and endurance > 10⁵) and sub-μA switching current are both demonstrated. The sub-μA switching current and self-selection nonlinear I-V characteristics are attributed to the SiO₂ interfacial layer rather than the decrease of conductive filament (CF) 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 can constitute workable 1 Mb crosspoint array when feature size scales down to 10 nm according to the HSPICE simulation.